what if I couldn't get to the apple store within a week after I bought something in the apple store

What if I can't go to the apple store within a week after I buy something on the online apple store?

I'm going to buy something soon, but the days I can pick it are limited only 3 days like 27(M)/28(T)/29(W). But I'll be there in 7 or 8 days.

If that happens, will my order be canceled?

or could I send an email about my situation and make them understand me, holding the stuff a bit longer to them?