Blood pressure med (HCTZ) caused ED so I changed to candesartan. How long should it take for my sexual health to go back to normal?

Unlikely. It's unlikely although possible that HCTZ (hydrochlorothiazide) caused your ED. ED happens to everyone some of the time. HCTZ (hydrochlorothiazide) has a maximum half-life of 15 hours. It will be completely out of your system in 75 hours (3 days).