Hi
First of all - good luck.
Second, the TAM is less important, the SOM (relevant Share of Market) is the important piece of the TAM, and this is much smaller. Either way, not everything that shines on paper shines in real life, or as mike tyson said: "everyone has a plan until they get punched in the punch" - in this case, business plans often don't survive reality.
1. My advice: unless your service is something that already exists in the market and has been proven to work, I would wait with the business plan (BP) and instead create a Business Model Canvas. If you want to write a BP nonetheless, I would be happy to review it for you (I even teach a course on it).
2. Stage 2: create an MVP / validate your idea. I am happy to explain to you exactly how to do this. Doing this properly, will save you a lot of time and money down the line. [see more info on validation in one of my previous answers: https://clarity.fm/questions/6423/how-do-you-do-market-research]
3. Improve MVP + create deck + write BP (only if you need investors which I assume you do because you mentioned the deck). I can happily give you comments on your deck, refer you to someone who creates beautiful decks at reasonable prices, and help you prepare your pitch via online video chats.
4. Create (almost) final version of product.
The MVP is the most important stage. It doesn't even have to be a working product to first check the demand in the market.
I've successfully helped over 300 entrepreneurs and would be happy to help you. After scheduling a call, be sure to please send me some background information so that I can prepare before - thus giving you maximum value for your money during the call itself.
Good luck

Great to hear!

CUSTOMER DISCOVERY
Your first step is to talk to customers to determine if this is something they would want. The best way for you to find out if your market has interest is to talk to them early and often.

MPV
Once you've determined there's enough interest from the market your next step is to make an MVP. The simplest possible version of your solution that will still appease your customer. Once it is ready, bring it to them and have some early customers try it out. Get feedback very early in the process! Don't build too much before getting lots of feedback.

IMPROVE PRODUCT
As you're getting feedback continue to improve the product. Be careful not to build too many features just for one customer.

PITCH DECK & STORY
Once you have enough traction, you can share you story with investors. There's an entire process involved with finding investors as well as constructing a pitch deck and a story. I've worked with many tech companies who have raised money to do that.

Feel free to call if you have any questions in your journey!

Hello.
An earlier answer of mine on similar subject may also be useful.

https://clarity.fm/questions/6349/answers/20321/share

TAM is a useless number here. What is more relevant is what is the immediate market size that you can operate in - say in the next 3-5 years - Total Capturable Market - TCM.

Right now my sense is for you to to create a value proposition or positioning, and then develop a prototype, validate with design thinking principles, define scope, develop MVP, get paying customers, and then execute per the plan recommended in the link above.

I think you are trying to jump from an idea and TAM to an MVP without going through the stepping stones to the same.

Hope this helps. Bye.

yes, you should think about MVP, This model can save you money and increase your business. here are some insights which help you
(MVP) A minimum viable product is a specific type of product that has a satisfactory amount of features that should attract the consumers or people who have just started to use that. That also works for the product idea which is in the development cycle and yet has to be launched.

Especially when we talk about the software industry. The MVP technique helps the developers to collect feedback and use it to alter or add features to that product. The process of user interaction becomes one of the most important things for agile development under the umbrella of MVP.

Benefits of MVP
The main advantage of a minimum viable product is that you can get across your customers and knowing their interest is one of the most important things to bring success to your product.

When you as a developer start to find out about the customer’s interest and whether they would love your product or not then create the product according to them and it also helps eliminate the unnecessary items from the product. The minimum viable product can have certain reasons to exist;

The company wants to launch it in the market quickly
Checking the initial idea
Learning the response of target market and target audience

Analyzing Market Demands
MVP is as powerful as marketing, and it is indeed one of the best marketing strategies too. With the help of MVP products, we can figure out our potential target audience and users. We also check the demand of the market. And that is also a major purpose of the existence of MVP products.

Testing Usability
One of the main benefits of MVP is testing the usability of the app. According to the statistics many people keep using the app if they like the interface, however; 21% of people abandon the app on their first use. And experts suggest it is the user interface that they did not quite like. And MVP offers a great opportunity to know what kind of UI/UX people are searching for.

Defining MVP
Let us talk it further and get to know how you can develop an MVP product. And how would the developers know whether or not you have developed a Minimum Viable product which is working and now ready to set in the market? So let us discuss some strategies.

First of all the MVP product has to be aligned with the business goals. When you start to plan your MVP product, make sure it reflects the goals of your business. Thereafter you start to focus on developing features. From the beginning, you should map out the product features.

After working on your goals you can now work on the solution which you will be provided through your product, to do that you must make a strategy and to do that you need;

Proper market research
Analysis of your competitors
Receive feedback
Determine the cost to implement it
Make a development and action plan