I've been all over "low dose" (dr approved of course) and currently at about half of a "typical" dose. I THOUGHT I felt a lot immediately, but it's more of a slow steady progression. I generally find about 3-4 weeks to really adjust to a new dose and for me at least the changes can be subtle. I have never felt smacked in the face, but I keep looking around wondering why I feel SO GOOD! Trust me...it's working girl!