A friendship bracelet question?

Well it really just depends in how strong your wish is and how badly you want it. Yeah maybe untying it wasn't a very good idea, but it doesn't mean it wont come true, it might just take a little longer. But the way this type of superstition works is like a reminder to be conscious of your wish since its something (bracelet) you have on all the time, this is why she told you not to cut it. Basically just make the wish again and feel it, put on the bracelet with as much faith as the first time and leave it on for as long as you want to.