Winter is the best season for an indoor sativa grow in most temperate climates. The heat from the lights becomes useful instead of something to fight, humidity is easier to manage, and the long cycle fits neatly between the end of an outdoor season and the start of the next. The seasonal planning notes on https://hazesativaseeds.com suggest starting long flowering lines in November so they finish before spring temperatures start climbing. The one thing to watch is cold air coming in through the intake, which can chill the root zone in pots sitting on a concrete floor.