To elaborate a little bit more on this part… the first three review sessions for a new learned item will be within 48 hours after you’ve learned the item if you get them right. Therefore after learning an item you’ll review it four hours later, then again eight hours later and then 23 hours later.
In case you want to read up more on the SRS feel free to check out the ultimate guide or wanikani knowledge base.
You don’t have to do all your reviews in one sitting. For example, I usually split up the total number of daily reviews into 2~4 sessions (approx. 15 minutes each) depending on my RL schedule. Feel free to try out to limit your review sessions. Experiment with the length that is comfortable for you.
Another thing to keep in mind: if you do a lot of lessons in one go (even if you apply the different advice people give you here) or do a lot of reviews with items in the same SRS stage in one go those items will come back at the same time in the future. Therefore, feel free to experiment with spacing out lessons / review sessions over the day. You don’t have to log in into WK every hour but maybe two or three times a day can do the trick.
Anyway, good luck with your studies and feel free to keep us posted 
EDIT: corrected the time intervals for the first three review stages. Thanks @Mrs_Diss san