Just make sure, whatever 'routine' you have after-school, or treats, is something you CAN keep up.
I learned, that once I started a simple 'once in a while' treat after-school, my daughter or any kid, will then want to have it everyday. Not just once a week. They will ask, whine, ask, and nag about it.
At this young age, they don't know what 'once a week' is. So for them, they want it everyday. Which may not be a 'habit' that you want to start.
After-school, we come home. My daughter unwinds (which is important for a child after-school. They need to deflate) and she can relax as she needs to. Then she typically napped after preschool. After school, she was TIRED and fussy. At that age, kids still benefit from naps and need it.
I always also give my daughter a snack at home... but not much 'sugar' based things. This is what I did, since my daughter was in Preschool and she is now in 3rd grade.
I didn't treat everyday after school was "special" and she 'had to' get a treat. Otherwise, they will then expect it everyday.... because it is the 'habit' YOU instigate as a Mom. And whether you can or want to do that, everyday. Afterschool. Or per your own after school chores/household things you need to do, and also incorporating that into the after school routines.
all the best,
Susan