Broke 1st metacarpel 7 weeks ago, cast off after 5 1/2 weeks. Have regained full range of motion / discharged. How long before playing goalkeeper?

Now if pain free. This fracture should be well healed in 6 weeks. The best indication of fracture healing is lack of pain, especially with activity. Start with some soccer goalie drills and see how you feel. Progress to playing from there. It is common to get some soreness when you start to use the hand. Ice and nsaid's will adequately treat those symptoms.