The pace is pretty much set to help users avoid burnout at later stages. In the early levels you don’t have items from months ago coming back for review on top of the more recent ones. There are fast levels (around 3 1/2 days at max speed) and normal levels (around 7 days at max speed). Levels 1-2 are fast levels but you won’t see another fast level until you reach 43. So you can expect to only level up once per week at best.
If that time frame isn’t going to work for you then It might be best to use another method (or supplement WaniKani with the items you aren’t going to learn in time). I’ve personally found WaniKani to be the best method for long term retention I’ve used, so I recommend sticking with it if possible.
You can find a more in depth explanation on how leveling works (and lots of other useful information) in jprspereira’s Guide