Usually my custom listings are gone within 24 hours, but I have one since last week....and nothing, just other people checking it out. I think is ok to leave it for some time, maybe after this weekend I will convo the buyer. So far it is almost like the ad in my store :) And also most of my clients are moms, and knowing life things like to go off the track for most of us, so I don't worry much about late claims for reserved listings. If I won't sell it, somebody else might buy it, or it will be great gift for one of my kids friends.
Just a thought...
Usually buyers are committed to custom orders, don't worry much. I think covo reminder after few days might be a good idea.
Aneta