One coat or two?

Hi!  I live in Kansas, and have a covered deck (not screened in) with stairs that get full sun.  It's cedar, about 16 months old, and hasn't ever been stained; no mold or mildew issues.  It has been power washed, sanded all over with 80 grit (the posts were rough hewn cedar and there were a few splintery spots we wanted taken care of for our kids) and we used the Defy cleaner and brightener.  We are planning to use TWP 100 series in Cedartone.  My question is: do you think one coat or two is more appropriate?  If we do one should we follow up with another in 12-18 months as I've seen you suggest with newer (4-12 month old) decks?  Thank you so much for this website - it's an amazing resource!