To be specific, you won’t have any enlightened items to review until you’ve been reviewing items daily for a little over six months. This seems like a long time … for about six months, then you stop thinking about it. 
@Mo-Kanji: Note that until you start seeing enlightened items in your review queue, you won’t be able to gauge how hard your workload really is. It can be eye-opening to review an item that you haven’t seen for four months.
Every review and lesson you do today will affect your workload for months in the future. As stated by others, a common rule of thumb is to pace your lessons such that the number of apprentice items remains below ~100. A better one IMO, is to keep the number of apprentice items + guru items/10 under ~150. It’s hard to get into too much trouble if you follow this advice. (I even wrote a userscript to make this more visually manageable.)
I’ve mostly done just one daily review session for about 2.5 years continuously, and have been averaging around 150 reviews per day (and 2-3 weeks per level) for most of that time. That’s just one datapoint (many prefer to go faster, others slower).
Doing just one session per day (if that’s your question) doesn’t let you catch the 4hour and 8hour schedules, so tends to be much slower than 2 or more sessions per day. If, like me, you choose to only do your reviews once per day, I STRONGLY recommend also using the extra study feature for recent lessons prior to doing your reviews.