Any sun exposure for 6 months post-laceration (including surgical) increases the risk of scarring. This is particular true of facial lacerations, but it also applies anywhere on the body.
If you tan, you'll increase the risk of scarring. No questions asked. How much scarring depends on your body. Don't take risks. Just be un-tanned for a while. You'll live and be happier than being tan, looking good for a while, but then having this ugly scar for the rest of your life.