No it is not too late, although if you have waited this long you may be sad because the price did a x4 in just this last 8 months. I believe in time a 10k bitcoin is not very hard to achieve so no it's not to late, not this time at least.
I would wait for the next 20% drop of btc, but I agree now is always the best time to buy btc. and 10K usd is only 2.5x away. so it will reach that 10k in 2018
If you study very well the price movement of bitcoin you will realize waiting for the price to drop by 20% is not be a good idea or a nice advise for someone who want to invest into bitcoin to leap into because ever since the SegWit was lock in bitcoin was stable at $4000 and after the final activation of SegWit anything can happen mate.