I personally found that it took a few days to kick in, but it lasted about one to two weeks. Everyone differs I guess.
The dream induced suggestions preceded a run of 2 weeks where I had an average of 1 LD a day

Like I say, on the occasion that I do not get a lucid dream, I use the wake induced version. (thats if I wake up early enough)

Good luck with tonight (unless its morning for you ...)