When Maggie was spayed, she was kinda out of it for a couple of days. I hadn't come up with my Softee Collar then so I put a onezie on her. Well it helped until she peed right thru it! lol The other thing you will need to do is watch and make sure that it doesn't irritate the incision site.
Anyhow, like YorkieMom6 said, you really only need to have it on if she's messing with the incision site. That's what is nice about my Softee collars...you can leave it on without it be a hinderance or nuisance for your poor baby.
Good luck and I hope your little recoverys quickly.