Greetings! 1st post here, however I do have about 40 years of vegetable gardening experience. (The 40 is not a typo. so bear with me.)
The best time to start mache, is in the fall when the temperature cools down. It is temperature sensitive, I have had it self sow during the summer.(it gets bitter in the heat) and then geminate in the early fall. Michigan winters.
It is very hardy and I have picked it in Dec. and Jan. under low plastic tunnels. Pest resistant except for the rabbits. Hope this helps. Cheers!