Do I really need to leave my phone off for 24 hours after I install this? Really? No, really?
Well it really depends. If your iPhone is really wet, I'd wait that 24 hrs. Otherwise it should dry up fairly quickly within a couple of hours.
BSE obviously want customers to wait 24hrs to remove any risk of damaging the phone but it's really your choice.
Personally, I've used BSE products 3 times and I installed them just before going to bed, so when I wake up in the morning, it's dry and ready for the day