How much knowledge about Bitcoin do i need before i start investing.
You will be able to tell if you have amassed enough knowledge because you will be very confident in your investment. But I would recommend reading the pinned topics (https://bitcointalk.org/Themes/custom1/images/icons/show_sticky.gif)of the beginners & help board to get started.
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.
Feel free to buy less Bitcoin for the same amount of fiat later. 
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?
You can learn more about Bitcoin on this forum. Welcome to Bitcointalk.
I was told same thing. So many advise i don't even know who i should respond, some said i shouldn't invest now while some reject and said i can DCA, not confused because it's left for me to decide on what to do.
Thank You.