I wouldn't know exaclty how long, but imo I would put them in a dark place in your tank. with very little light. it may inspire them to come out faster...
Last time I got some zoos and they didn't open right away, I was told it takes a few days... but then they just melted away. All of my other Zoos and Palys have opened up within 30mins after being put into tank sometimes even before acclimation was done.
I usually take about an hour to an hour and a half to acclimate anything that goes into my tank, this way I have a lot of time to inspect it for anything bad.
It can take longer for zoos to open when they've been shipped versus picking them up from the store or a fellow reefer because of the time they've been in a bag. I've had some that have shipped that have stayed closed for 6 days before they opened and they were fine, but if they start to melt away in that time you can be pretty sure they're not going to make it.