How much knowledge about Bitcoin do i need before i start investing.
As much as possible. The truth is that just like any other knowledge, Bitcoin knowledge has no end point and you can not graduate from learning it. Normally, knowledge is a continuous process and at every stage, you keep learning new ideas.
I want price of Bitcoin to reduce so i can start my investment, anyone knows when the price of Bitcoin will fall so i can begin.
Nobody can tell when the price will go low to your desired expectation but this statement is normally attributed to people who have no zeal to invest in Bitcoin. They keep giving excuses of high price while the price continue to soar higher and they'll be expecting a more dip even when the price drop a little that they can easily take advantage of DCA. It's purely a showcase of lack of interest.
I did not take my opportunity when i was introduced to Bitcoin and this forum, what should be done to correct my mistakes or am i late?
No, you're not late. Some mistakes can not be corrected but keeping doing same mistake is insane. The good thing is that you're here and ready to begin the journey. Your action henceforth will determine whether you are late or take your opportunity this time.
If doing both will not cause me harm then i will like to do both, only one to be picked then since i do not have knowledge about trading, investing will be better. Where can i also learn trading?
To be frank with you, trading is not for people like you. You said you don't have knowledge about Bitcoin and you want to jump into trading? How do you intend to succeed? You must definitely have knowledge at least, the basic before you think of trading because you will need it to survive in your trading journey.