I understand how you feel. Can I tell you an exact time that you wont think about him? No... You might stop for a while and remember again or you may never stop.
I think all of it stems off of what your current BF isn't fullfilling and the fact that your ex did.. Or thats how you are choosing to remember it. The fact is even though you don't love your ex anymore there is a reason why you broke up so its obvious he wasn't fullfilling everything for you.
I date a man for near 2 years, he was my first love. Things were good until they weren't, it all happened very fast in the end.. I was 19 when we broke up, so a baby still lol. But sometimes (especially right now for some reason) I still think about the relationship. The good, bad, and ugly. It makes me sad that I still think about the relationship and two very different people we are now. (We are still friends with mutual people, but haven't spoken in nearly 3 years)
I am now happily married and have been with my husband for nearly 2 years now. I love him and I am so glad that he is the one that I am spending my life with, but it comes down to the fact that I compare sometimes. My DH has hurt me in the past, much worse than what me and my ex even broke up for. So sometimes I think about the fact of what if we had been able to work it out like DH and I had been able to in the past. (Though, I am still happier with DH) Also I really big part was I was very good friends with my ex for many many years before we actually dated. Sometimes I simply miss that friendship we had sometimes. We were best friends for about 4 years before we decided to try a relationship.
ANYWAYS I am rambling about my past plunders.. What I am trying to say though is... Your ex is a memory in your past, though you may not still have feelings for him you still might think about him. You may want to evaluate your relationship with your current SO though. If he isn't emotinally fullfilling then what do you really have? The more you WANT to let the memory of your ex go the more you are probably going to end up remembering.. So just go on about your life. If you think of him then only let it be for a moment and then move on. In time it becomes less especially when your life moves you further away from where you were then.
I'm sorry to ramble... But I really hope that helps