yea well you might want to look in to that ventilation/filter set up before the end of this grow, once in flowering they will stink !!
but do as me, get it up running like you have now and wait until next pay check/safe up to buy it, then its also about time to flower Im sure, a budget kit can be found for for around 100$
like this one:
http://t0ko.com/home-appliances/air...room-ventilation-160-cfm-carbon-filter-4-fan/
filter like bulb`s last a year roughly (I first fit mine in flowering/when they start to stink) ventilations can last for years, mine have now been running for +1 year 24/7 and both clear the odor in flowering, and provide fresh air/co2 for my plant`s and help keep it cool (tho I use LEDs now

)
IMO a must have, fresh air circulation is so important for them to do good and the odor control equal important to stay stealthy and be able to live in there