How long is too long to ship out an item you've sold on ebay?

So I've just sold my first item on Ebay. The buyer had already payed for it, so I've already checked "mark as payed". I was planning on bringing the item to the post office to ship it out today, but I just noticed I bought the wronggg type of envelope, and the post office is about to close :/. So tonight I'm going to buy the right type of envelope, and then mail it out first thing tomorrow morning.
Would this "take too long"? Haha sorry it sounds like a silly question.

If your buyer has paid with PayPal linked to a credit card..ship it tomorrow.
If by cheque,,wait till the cheque clears the bank.
4-5 days is quite acceptable.

Source(s):

Knowledge.