Hey! We were there in early February and they definitely had all the pool activities- several times a day. Also, the pool is heated. I'm glad of that because it was cold when we were there!
Also, if the pools are closed (like if it's raining, etc), they have the activities in the mall area.
We just returned from a visit to the Nick Hotel. We were there on March 23rd to the 25th which turned out to be rather cool (high 60's/70). The pools were heated fine. However the water slides were not. I put one foot in the large slide complex and it was way too cold for me. The slide at the oasis pool was a little bit better. My kids were fine for a couple of hours on the slides but then even they got cold. The pools themselves were fine but I felt like we didn't get full use of the slides because they were pretty cold. Also, the slides closed at 7 p.m. because it was so cool.
I personally would be hesitant to go in January because the weather could limit your slide use (one of the big reasons we went). But you never know, the weather could be great!