From the picture that rat looks appropriately sized.
Believe me when Snickers gets full grown the mouse feeding thing will get really annoying lol.
Most people have to do a "zombie dance" a rodent in the wild would be moving and it only natural to have to mimic that.
The way you word him "eating from his dish" is almost comical.
Ball pythons are notorious picky eaters and Snicker's may develop some feeding issues. Like you may need to do the zombie dance now, or he may go on small fasts.
If Snickers is just a pet I would think a feeding of every few weeks of an appropriate sized meal would be just fine. But you sure can feed him once a week if you'd like.