i use revolution (selamectin) from the vet and it’s like a fucking flea nuke. if you’re getting it soon i wouldn’t worry about fleas getting in the house because once you use this stuff it’ll clear all of them out of the area in literally hours. fantastic stuff.
also, don’t trust any over the counter flea sprays or treatments at stores, they all use neurotoxins that they claim is safe for cats, but some cats are more sensitive and it might cause neurological damage or even death.