Aw man...I'm jealous !!!
I never gave a "hotspot" per say (UTH) but I used a cage and it had a light above it and branches under the light, so they could climb up there if they wanted it "warmer". They did occasionally, but they seemed more bothered if the house got to hot, rather then being cooler.
But I would go by the breeders recommendations, esp. while they are so small. To make the transition easier.