When did your child show interest in sports?

My son is almost 3.5 and doesn't seem too interested in sports. I think its just too early but I think my husband is worried that he doesn't show much inclination yet. We make an effort to take him outside quite a bit and play with all different sports equipment. Just wondering when other people's kids seemed to take an interest. We understand he may not like sports at all and that is okay, just wondering.