Bought this rosemary from the grocery store, pruning and care tips?

It struggles a bit to stand up on its own, and it was kind of sad when I bought it, but a $3 plant is a $3 plant. I figured it needs pruning to get more bushy. Only has one main branch, still in the pot i bought it in. Is it still too young to get started with pruning, standing at ~15 cm?

Currently getting 4-5 hours of direct light, in a room with windows on every side except north, so plenty of indirect light. Supplemented by grow lights as well for the winter. Would love to hear fertilizer routines as well.

Thanks everyone!