How long does it take for a first degree face burn from waxing, to heal? will it keep scars?

1-2 weeks.: First-degree burns -- superficial ones that are red, but not blistered -- generally heal within a couple of weeks, without scars. You can apply a mild otc Hydrocortisone cream sparingly twice a day to speed the process along a bit, if you wish. "burn creams" like silvadene (silver sulfadiazine) are unnecessary.

No scars; heals fast: As long as there is no additional injury! if you truly have a first degree injury, that means no blisters of any kind, and avoiding any additional thermal or abrasive damage will prevent any scarring whatsoever. But your skin is more sensitive now, so be careful about sun, freezing, or vigorous washing or exfoliation until the redness is gone! it should take a few days at most.

Depends: If it is truly first degree and does not become secondarily infected, everything should heal fine. One should be careful of subsequent sun exposure to avoid hyperpigmentation.