How long does it really take to be cool with your ex?

If you mutually and amicably broke up. I care about him so much and want him in my life but I'm kind of still hurt and upset, I miss him terribly but don't have any desire to talk to him right now. Will I ever? Would like to hear from folks who have maintained a friendship with their exes, specifically how long it took, and how long after the break up you went with no contact. Thanks :)