After 3 weeks you have likely not lost an enormous amount of fitness.
I highly recommend jumping into our 6 weeks till CX plan. That will help get you set up for your cx season. Do the basic level so you can ease your way back in. Then do our cx intervals plan and for that one you can bump up to the intermediate level as you have done in the past (or stick to basic if that creates a better work/home life/training balance).