I broke my third metacarpal. What is the expected recovery time?

6/8 weeks. Gennerally speaking, with normal healing under typical circumstances, return to light duty activities is commonly permitted by 6-8 weeks.
8 weeks. The metacarpal bones, if well aligned, will take 6-8 weeks to heal. However, the bone will require another 4 weeks to remodel and to regain its original strength.