You can see that bitcoin was falling a month ago. Now it is rising you can buy now some bitcoins. You only have to wait if you have done that. The prices are currently rising experts say that bitcoin will go to 10k in the future. I would sell them when it hit over 10k you would have a massive amount of money.
Good time to buy any coin even Bitcoin is when the price is falling and it's low, not when it reaches all time high. Maybe it will continue to rise over 6000USD and you'll still make some profit if you buy it now, but sooner of later it will fall down, probably to around 4000 USD. So why buy it now it's better to be patient and wait until the price is lower so you'll get more Bitcoin for your money and when the price rises again you'll make more profit than if you bought it now.