Absolutely. Wanikani doesn’t force you to start new lessons if you’re not ready to (I recently let my lessons sit for three months to try to get my review count under control after a rough stretch over the midwinter. Most of the advice given out is to not binge through all the new lessons as soon as you’re able to keep the review counts manageable. The forecast is your friend in knowing if and when you’ll have a big pile of things coming back, and the Heatmap script can show you further out if you’ve got any bad days coming up.