When I started using the Hydroxtreme7, I used the clock on the wall across from the shower to keep track of time. It wasn't the best situation due to the nebulosity of assessing exactly when I would start. I did that for 1-1/2 months without noticeable gains; then I purchased the BPT.
The timer has made it considerably easier to use my pump at the recommended intervals: I start to pump manually, then start the timer once I can no longer pump water manually; at that point I then use the hand pump and hose for the Xtreme to ensure the pressure I want.
I can attest that, since using the Timer, it has improved my use of the pump, such that I have (after 3 months of use) noted approximately 0.25/0.35 inches in growth for girth, and about 0.25 inches in growth for length.
My partner has noticed the difference, even exclaiming one time, "WOW! You're so big!" She and I both appreciated our intimacy that day, and other days. (This was several hours after using my pump, while still partially flaccid. And though she always expressed satisfaction with my prior length and girth {appx. 7Lx6.5G when erect}, she has been especially happy with the increases I have thus far gained.)
So, even a small amount of gain can make a difference for your confidence and the experience of intimacy you and your partner share. But, as other reviews suggest, consistent use over an extended period of time will help you see the most gains. While my experience is anecdotal, I would thus encourage purchasing a timer for the sake of the benefit it can prove to you.