All of our cast iron is pre-loved but in your position, I would just rinse it to get rid of "shelf dust" from the store and then slowly heat.
Once you put a few DO meals under your belt, do a search of this forum for Dutch Oven Gatherings. I've posted a number of them including organizations and clubs that do those gatherings. The dutch oven gatherings are attended by experienced and novice cast iron chefs who are more than willing to share their knowledge, secrets and shortcuts of dutch oven campfire cooking.
Welcome and glad you joined the ranks of the cast iron chefs:B