you should have ventilation going at all times....cannabis loves fresh co2 all day long. ventilation also helps prevent pests, ventilation also helps with evaporation so your soil doesn't stay soggy.

ideal temps are around 70 or so, but every strain is different...some are more resistant than others.

other advice - make sure you have at least a 30x magnifier to check the color of the trichs, trich color lets you know when its harvest time. monitor your ph, use a bloom nute, if you want experiment using something like blackstrap molasses which can help increase the size of your buds