How important is ventillation during dark period?

I'm going away for christmas break for about 3 weeks but having a friend water the girl every 3 days. If there is an apartment showing I don't think they'd even go in my room much less likely open the closet but if they did I'd want my little plastic bin to be quiet instead of humming away. The lights are off from 9am-9pm anyway but it would be really nice to be able to have the ventillation fan (which is usually always on) be on the same 12 hours of dark schedule.

The box sits in a closet that isn't airtight but probably doesn't get a large amount of air flow. I only have one, 3 weeks into flowering plant in a medium large plastic storage container.

Could I just have the fan turn off during the day when the plant is already in dark period? Maybe just 15 minutes every couple hours? Actually showing are only from 11-5 so I could buy a separate timer and have it only be off for 6 hours during the day. What do you guys think?

Most of the timme you don't need fans in the dark stage. If they're heavily flowered with tight buds, thats when you need 24 hour fans to make sure you don't end up with bud rot.