I usually take creatine before and right after my workout with maltodextrin. Is it beneficial to take creatine on rest days too?
Yes, creatine can be taken on rest days as well. Here is an excellent article with research backed data on creatine:
Creatine monohydrate can be supplemented through a loading protocol. To start loading, take 0.3 gram per kilogram of bodyweight per day for 5–7 days, then follow with at least 0.03 g/kg/day either for three weeks (if cycling) or indefinitely (without additional loading phases).
As Creatine is stored in the body, you can take it any time. While some personal trainers recommend taking it after a workout, this has no difference in uptake.
I use creatine as a supplement for boxing, to increase endurance when I'm training up to a fight(I cut it 3 weeks before a fight to throw off the water weight that it adds. For me, it's around 2kg.)
I've experimented a bit and ended up taking the same amount every day, be it rest day or not. As far as I've read, it's stored and will just build up over time. This is of course assuming you're taking it consistently and not doing the whole load/unload phase etc.
So, to answer your question: It doesn't matter, take it at the same time every day for consistency. I'd suggest making it a morning routine.