to decide to buy you should not be in a hurry.
to what extent the price decline will occur no one can know for sure, but now it looks like the sharp decline has ended the price has stabilized in the last 24 hours. maybe if you believe that Bitcoin or Altcoin will be able to get back up at a time like this it is very appropriate to buy.
however,
Its hard to buy in rush situation since we don't know the outcome of the market at the end of the day also we should do more careful technical analysis on how the market flow since if we bought at wrong position then provably we will just get panic if the price fall. So best to wait for ideal price to buy since we don't have anything to wait and it seems we will not see any huge pump for this year.
If you just believe on bitcoin and you think for long term hold then maybe any price will be suitable since most provably in next halving we can see good price action towards bitcoin at that time.