You can never be sure.
At first you said you can never be sure you will be able to buy lower, now you say you can just never be sure (for anything). I like the train of your thought, dude!
But when you sell all at 400, and no correction under 400 happens next half year, when do you buy, never?
I could have said something about price going down to zero within the next three months, but what actually matters are relevant facts, not wishful thinking. Do you have any, pro and contra?