A good base of sealant shouldn't be effected that much from claying from what I've seen, now to be careful I ussually re-seal/ wax afterwords. for preparing my vehicle or any other i usually wash, clay, polish, seal, then wax. As for when it gets dirty again simply wash and wax at normal intervals or when needed, and make sure you do so correctly to not make swirls in the paint surface. I typically re-apply sealants atleast twice a year depending on the durability of them, and wax every wash. I also clay as needed depending on vehicle and contamination that is in the clear. (you can feel this after a wash.) Claying can be done as needed as well and really up to you and the condition of paint, then just go and apply sealant and wax.
By the way what products are you using? I have had great experiences with Optimum, Wolfgang, and Pinnacle products.
Good luck and don't get sucked into the addiction of detailing
