It really depends on the toy, and the time-frame I've set for the review. I'm working on a review now, and I think I've already used the toy 4-5 times. I'll probably use it at least twice more before writing my review though.
Some times, however, I'll use a toy 10-20 times before writing my review.
I put 4x. I would have checked "other" if it had been an option. There are some toys that only need a couple of "tests" and there are toys that require more. For example, if I have a dildo that I know works well vaginally, I'm not going to write a review until I've tried it anally. Unless the girth is too big or the ridges are too much vaginally, in which I include that it in my review. It all depends on the toy, but I like to get a good feel for the toy before I share my opinion on it.
I was wondering how many times or for how long should you use or have before posting a review for that item.
That's actually tough. If they toy doesn't fit, was painful or a bitch to use I may only use it 2 or 3 times but if I enjoyed it I will try it out up to 12 times before writing a review so that I can give that much more detail.