Olives are real hardy. We regularly dig wild ones and chop the trunks in one operation so they respond well to root reduction and pruning.
The real question is whether you should trim this little baby. If you just want a small, thin bushy tree then go ahead but if you aspire to a thick trunk, old looking olive bonsai it's probably advantageous to let it grow (a lot) because increased growth = increased trunk thickness. No problem with olives getting big because they can be chopped way back and still produce new buds, even on old, bare wood.
BTW. Best to add a location to your personal profile. Time of year can be critical for many bonsai techniques and species of tree. It may or may not be a good time to repot olives depending where in the world yoTs u are.