How much time is allowed to lapse till you can't open a case?

[mimya3]

Hi,

I sold a top on ebay and the lady can't pay with paypal till she's back from holidays on the 5th of May....  It sounds a bit suspicious to me; as if you can email surely you can pay with paypal?  Anyway, I want to give her the benefit of the doubt and allow the transaction to go through.  But I don't know if there is a time limit after selling an item that I need to open an unpaid case in??  Help!!

Thanks, mim.