The WaniKani Heatmap seems to think I spend about 45 minutes a day on WK. Although that’s 7 days a week and while I make consistent progress it has slowed considerably since the early levels. I noticed a ramp up at level 7 and then another at level 13. The first 10 levels took 5 months, the last 7 have taken 9 months. Really looking forward to the Death levels. 
You can do it, but I think you’d need to go slower than I am, and perhaps turn on vacation mode for the 3 days a week you are away from WK.
Despite my pace, I do notice progress. At present my main concern is forgetting all the burned items before I finish.