I keep track of where my items are in the srs timeline. I use Flaming Durtles on my phone for a quick look at my 24 hour timeline every now and then during the day, and what srs stage those items are in. And I also use it for a view of what my current level items are doing (how many are in what apprentice stage), and what previous level items I haven’t guru’d yet.
For a cumulative count of my reviews in a day, I use the new dashboard hourly Review Forecast. I can tell from that how busy I’ll be when I sit down for reviews at various points in the day.
Furthermore, I only do lessons in the morning before 8, and make sure I can get to the next review before 1pm. That way I can do the next review of those new items before 9pm in the evening, when I am usually not so tired yet. That greatly reduces my mistakes on these critical items that contribute to immediate workload the most.
At one level a month are you doing a set amount of lessons each day? At that rate, you should be doing 1 or 2 new kanji each day, and you can spread out the vocab very well, too. Doing less lessons at once might help to increase retention, because you can pay more attention to each item. And give attention to older items coming in as well.
In short, I pay attention to the amount of reviews coming in throughout the day, so I am never surprised, and I do my lessons at a set time, at an amount that allows for me to keep pace, and set aside time to hit the reviews of those lessons on time.