Our customer identified a check they wrote had been altered to an unknown payee for a much larger amount 4 days after it cleared their account. Our customer's signature was photocopied onto the fraudster's check stock and the words "VOID" appear faintly on the background of the fraudulent check. We are the paying bank and in a panicked reaction, returned the item which was a late return. I read where the depository bank has 3 years to reject the late return item and I fear they will wait until our 30 day timeframe to be able to send the breach of presentment warranty claim has passed. I'm assuming it's not reasonable to file the claim before the 30 days when we currently have the credit from the late return? Is there anything we can do besides wait for the rejected late return item and then eat it?

Your description sounds more like a counterfeit check than an altered check. "customer's signature was photocopied onto the fraudster's check stock." If the check is not the same check that your customer issued, then it's counterfeit (forged drawer's signature) and not altered. In that case, there's no presentment warranty that has been breached.

But if it was in fact an alteration of the check that the customer issued, nothing prevents you from sending the notice now. You can send a letter notifying them of the breach and just note that the check has been returned so at this time you're not demanding payment.

Do we have any recourse that the check had the "VOID" verbiage in the background when they accepted it?

No. There's no warranty that the check was validly issued, only that they don't have knowledge that the drawer's signature is not authorized. Not that it makes any difference to the analysis but the check also had the "VOID" verbiage in the background when your bank paid it.