is this the right moment for pick altcoins with BTC
Yes.
what do you think will be the lowest price in this summer ? wait more =?
Price for what? bitcoin? if you're asking about bitcoin it should be $7,500 down to $7,000 and that can be the bottom price for it.
How can you say that 7,000USD is the bottom when price was many times under this price. Also today price was under 7,000USD. The bottom is arround 5-6000USD. 6000USD is very strong support, price fell down to 6000USD many times and this support it lasted.