@BroadwayCovers on Twitter usually has up to date information because the information is crowdsourced.
The thing is though that you don’t often know in advance if someone will be out unless they have a pre-announced vacation (which would be listed on SeatGeek, eg. Gavin Creel), or COVID (where you can ensure they will likely be out from 5-10 days)
Check out my eBay page for sales on Playbills!!
www.ebay.com/usr/missvirginiahamm