Today is the best time to buy because as we noticed that the price is still low and looks like it will increase on the latter part of the year. Since the price is low, just buy now and hold until the price will rise up soon.
Highly unlikely that price of bitcoin will rise in summer, when most of the traders are on vacation.
A good time to buy now

Might be, but we're still in bear market so i wouldn't be buying for whole money, for 30% of the deposit for sure.
Even though possibility that we go 5.500$ per bitcoin remains, i do not believe that we will remain in this price range for long, as market tempts to turn now, but doesn't have enough strength.
Price of bitcoin is still very small, so if you look long term on this asset it doesn't really matter if you buy it for 6300$ or 5800$, as time shows people who just HOLD, make profit 10 or 100 times more than daily traders.