There are many threads on this, but I think the bottom line is that there is no set rule on what the "acceptable" time limit is. I think your guests will understand no matter what you decide (within reason...it's not like you want to do it 2 years later, lol). I've seen lots of brides comment about the timing of their AHR and they vary from a week after they return from the DW, up to a year later. There are many reasons for the dates including what works for their schedules, the weather (for an outside AHR), financial reasons, etc. So just do what works for you and it will all work out