Ooh, that green zone, I see, my bad, I thought you were speaking of another metabolic zone similar to the easy green aerobic threshold Byrn speaks of.
Yes I’m starting to digest all those concepts, and just starting to implement them, at least in my mind 
. Up to this week I mainly went by listening my body, spending much of my slowly increasing time in z1+z2 hr, mainly walking with more n more biking, and backing off for few days as soon as felt a pain somewhere, happened mainly on a knee.
Now that body seems to better respond, I went full bike this week and gonna try to start periodisation, by increasing the load (volume) each week by 10% for three weeks followed by a recovery week. I’m not sure about the load of the recovery week, I guess half the preceeding week load would be ok? (EDIT: already answered here) Same for the 2 recovery days per week, I plan riding at half my fitness.
As for the season goal, I don’t have one yet, I just want to increase my endurance fitness until I can make good use of the smart trainer I plan to get for Christmas and the road bike I will get next spring. Buying a mountain bike as a first bike was not really a smart move but I got inspired by the surrounding wildness I live in and new nothing about sport and training. Have to start from where we are.