It totally depends on the quality of your application and that seems reasonable. You will have to wait for them to respond. They take a lot of things into consideration before making an offer. I am sure you will get LOA as you have supervisor confirmed up front. So, just wait for now and do your best to provide them any and all documents you are requested.
If you have applied in January this year then there are two possibilities:
1. Your application is considered but is in the waitlist. Meaning they have made initial offers and they will see if some candidate does not accept then they will call the backup. I am just assuming. This might not be the case. It totally depends on the Department you have applied to. My Department notified me on Feb 27 that I am accepted with funding.
2. The Department you have applied to is yet to undertake a review of all applications submitted for Fall 2019.
In either case, you will have a response soon as it almost mid-March.