I recommend to wait until the bitcoin price is confirmed to be stable. But if you want to take risks then now is the right time.
You can speculate to get big profits and also could lose big too.
That's right, anytime you could invest on bitcoin. However, just wait for the august 1 to come on its end and wait for the result of the segwit. On the other hand it is also better if you invest now but it there's a risk attached from it which is you could lose a big amount of your money.