You can definitely give him 2 or 3 of those at a time per feeding, those are way too small for a proper meal. It's always better to give them a full appropriately sized meal within a day, rather than feed frequent small meals. Just after he swallows one completely, wait a couple minutes and offer another.
A good rule of thumb for young ball pythons is their prey's width should be the same or slightly wider than the thickest part of their body. Usually it is around 15% of their weight.