How long is reasonable to receive payment?

[MirandaWest]

Sold some clothes on eBay finishing on Sunday evening. Have received payment for all except one buyer. They had bought two items so did combined invoice which I sent on Monday morning.
Sent them a payment reminder yesterday morning - I see that people are meant to pay within 48 hours (so Tuesday evening technically) but still nothing. When is it reasonable to start the unpaid bidder process?
Was thinking of sending another reminder later on today or tomorrow but not sure how long is reasonable to wait for payment (there's been no communication from them at all - if they had been in touch then would be slightly different).
Their past reviews vary between paying very quickly and it taking a while so am guessing they're in a "taking a while" phase but I would like to get paid. There's also other bidders I could offer the item to.

[TeacupDrama]

Start a case joke then they have 4 days, don't bother with more invoices you should have started the case yesterday you can't offer items to other bidders until case closed so if you start this morning they have till Monday morning to pay

[19lottie82]

I agree with TeaCup - Open a non payment case now.