We used it for 18 months (we discovered some time after buying the lube we had reversible fertility problems). Once our fertility problems were reversed, we were using it the cycle I got my BFP. Honestly? Please don't pin all your hopes on it magically giving you a BFP. View it as a useful tool to aide sex and conception where normal lines would hinder. (Hope I don't sound too cynical). Also, a word to the wise - it's fricking cold! Warm it up in your hands before putting it anywhere delicate All the best TTC.
We used it for months and nothing (although recovering from ectopic and tube removal). Moved to pre seed. Nothing for two months when I used applicator (possibly too much?). Started Acupuncture, used pre seed on hubby and BFP three week later...also before more fertility investgations/possible obdurate (had given up, he he!).
Another one here who used it and fell pregnant second cycle. In fact, we only had sex twice in the second cycle as we thought we ought to avoid a Christmastime baby...due 24 December.
However, massively agree with the poster up thread in that it may very well have just been our time and nothing to do with the lube. I wouldn't hold out all hope on it, but would certainly say there's no harm in gong ahead and using it.