Botox - how can you tell when it's fully worn off??

[wantingresults]

I got botox a little over three months ago but got some odd new lines appearing that I don't think were there before. I have been waiting for it to wear off as I found a new doctor who thinks he can get a better result next time around. But I can't figure out how you know when it's fully worn off. The "new" lines are still there which makes me think it hasn't but I think some of the lines that the botox got ride of may have started to come back. It's hard to tell though as I got a very small amount so the area wasn't perfectly line free and I'm also in my mid 30s so didn't have really heavy lines to begin with. I can't remember how bad I was before! And maybe the new lines have become permanent and will remain even when the stuff is out of my system?! Is there any scientific way to tell?

[wantingresults]

I should add that I've read it takes 3 to 6 months to wear off depending on your metabolism and mine is annoyingly slow so I'd have guessed it might be neared to 6 months...