BTAs are pretty resilient, it will be fine.
When I receive shipped livestock at my office, it's usually sitting in its bag until I get home in the evening. They're no worse for the wear. Once, UPS misrouted a shipment from Live Aquaria and it arrived a day late. Everything survived and is doing well.
Once the bag is open and the water is exposed to air, the ammonia in the bag becomes toxic, so that's when time consideration becomes important. Thankfully with anemones, you can just temperature acclimate and then place them in the tank.
Sent from my iPad using Tapatalk