I’m pretty sure one of the guys from the store will be there to check out your instrument. Might want to contact the store or @aliciabowman ahead of time just to make sure.
If you’re looking for an armrest Ben"s store has several choices (link below)
https://store.banjobenclark.com/pages/search-results-page?q=mandolin+armrest
Ir normally doesn’t take but a few minutes to install one and I’m pretty sure someone will find the time to help you out. Many people install them by themselves…it’s quite simple.