How soon is too soon

I would wait at least 3 weeks before anything intimet. But have some kind of phone or casual contact to carry you over. The more time that goes by before you get physical the less likely you are to use the person as a rebound. If you move to quickly the person you moved to usualy is just time fill while you are getting over someone else. Most people end up discarding them like a piece of trash on the road side. So make sure you take the other persons feelings into account. Which it seems like your doing. Try to put the other relationship out of your mind. Bond as friends first then take it to the next level. You will do fine

Personally I'd say it doesn't work, there's allways somebody who still has feelings for the other, and feel as if there's a chance that it could work out again.

On the good side, when I split up with my long term partner we couldn't stay friends, feelings for each other were to strong and as hard as it was we had to lose contact. 3 years later I bumped into her and we're best of friends again.

i dated an ex girlfriend for 4 years; a week after break up, she was already dating another guy.heh!
As for myself, I applied that philosophy of, you need to sleep with a few gals to forget her, so 2 weeks after breaking up, I was thinking.'why didn't I break up sooner?' :))
But seriously, it varies; I have had friends that go months, and others that go just a few days. Is what makes you comfortable.

It kind of depends on how long you were with the person but I personally believe that you should wait a good amount of time before you start seeing another person or acting on your feelings for a crush. It will be good for you and whoever you end up with in the end. Plus you need to make sure that you and your ex are comepletely over and are definitely not getting back together.I know from experience that if you still have feelings for your ex when you go into a new relationship, it can effect your new relationship because the person that your with is going to realize. I don't really think there's anything wrong with just hanging out with people and stuff, just take your time after the breakup and give yourself time to heal.

i think it's wrong to act on a crush, because that just makes you wonder how much ur partner already liked that person while you 2 were still together. my boyfriend did that, luckily it didn't work out, but it made me feel like shit. I personally can't do that, because if I would get with my crush, I would have to think about my ex and how we argued about that person, so I rather just meet new people.

Nope, I don't think you would be using them as a crutch in this case. If you liked someone while you were in a relationship then it sugests there was something wrong with the relationship anyway. So if the relationships ends in the meantime you are then free to pursue any other possibilities.
I think the answer to your first question is yes - it is normal.