By your question it seems you don't know about bitcoin well enough so please learn about it first, it will take very little time to gain basic knowledge about bitcoin.
I would like to suggest you some sites, guide, youtube videos, to learn:
A Guide for Cryptocurrency Newbies for Overcoming FOMO
learn me a bitcoin
Explain Crypto To COMPLETE Beginners: Coin Bureau Guide!! (youtube video)

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you can buy bitcoin by using exchanges there are centralized exchanges(needs sharing personal info and need to do KYC) and decentralized exchanges(do not need much info about you),

You can start your investment anytime but some reminders to remember.

Use your own money for investment because it will help you having better psychology in this volatile and uncertain market.
Don't invest if you can not afford losing your money.
Don't use any leverage for investment because with leverage, you will have risk of liquidation.
Invest in Bitcoin, forget about altcoins that will cause loss for your portfolio.

Invest with DCA strategy and with Bitcoin.
https://dcabtc.com/

Investing in cryptocurrencies is very risky, but you can invite good morning to bitcoins with much less risk.  The first thing you need to accept when investing in Bitcoin is that you must have a long-term investment mindset and you must have enough patience.  On the other hand you can follow DCA to further reduce your risk as you will buy bitcoins at different prices as you will not invest at one time and your chances of losing will be reduced. I think these are enough to invest in Bitcoin

Welcome to this my forum brother , yes truly betcoin is a good project actually and it will be in the future , for a good beginning you can use this forum by posting everyday or when you have time to do it just for fun . Your activities will rise every 15 days , you must upgrade your level , when you achieve full member you can start your real project by finding a signature compagne.. , or bounties , this forum offers you many chances and opportunities,  Good luck to you .