If I buy something before money is in my account, what happens?

You get screwed. NEVER spend money that is not already in the bank.

if u order smth when u know u do not have enough money on your bank account u will pay penalty. in my bank it is 50 euros

If your paychecks hit on Monday, depending on the time of day, it will clear on Monday, Tuesday or perhaps even Wednesday.

On the other hand regardless of when the check you wrote hits the bank MAY look at the date on the check and the balance then, and bounce the check.  Do not write a check that will overdraw your account.

We have no way to know. Some companies don’t bill until the item ships. Some bill at the time of order. You need to contact the company and ask what their policy is, but realize that it’s the weekend *and* tons of places are running skeleton crews.