My first experience with using a carnauba topper over a sealant was about 4 years ago, and it ended somewhat badly. I was using a combo of Klasse SG and S100 wax. Even after waiting a full day, I still wound up with the dreaded "SG haze". During my second attempt, I waited 3 days and still got haze. Afterwards, I became paranoid and began waiting a full week before topping. Using this process, I haven't run into any problems with any combination of sealant and wax topper since then.
I am a hobbyist detailer, so I have the luxury of being able to wait as long as I want for my personal vehicles. When I am operating with a time constraint (e.g. working on a friend's or family member's vehicle), I choose to use a single LSP. If I use a sealant, I will not top with carnauba. If I want to use a carnauba, I will skip the sealant. In many of these cases, I choose to go with a hybrid product like EX or PwC.