The last cross I made between a Chemdog x D NL#5 and a Godberry, was due to lack of smoke harvested after 45 days, this female Godberry had been pollinated at day 10 of flower, the 4 seeds I got look nice dark and healthy, which I found odd, hence from other experiences they need longer time to mature.
The time before that I pollinated some girls at day 14 and harvested them at day 60, all 55 seeds except for 5 were dark and viable, some are growing at the moment.
I would say wait at least 8 weeks to ensure the seeds are properly done and store them in the fridge...