Hi Gessie - If it's been 4 days, I wouldn't worry about her jumping up on things now.
Many cats are already trying to jump up on furniture the day after the spay! Cats heal much more quickly than humans.
I never had an E-collar for any of my girls after their spays. Unless Cosmo is biting at her sutures, it's unnecessary.
Just FYI, I recently saw an alternative to the E-collar in a catalog. It's called a "Bite Not" collar and allows cats to eat, drink and get around the house more comfortably than with an E-collar. They also have full vision. It's sort of like a turtleneck that goes from just behind the ear to the top of the shoulder. It's available from www.carealotpets.com
I'd remove Cosmo's collar and see how she does. Keep an eye on her, and if she's not fussing with the sutures, don't put it back on. 4 days is a long time to wear that thing!
Best wishes to you and Cosmo!