What Age Does Pomeranian Dog Go Into Heat For First Time?

Around 6-8 months of age but you should wait until her second heat cycle to have her breed.
At this age she is still a puppy and has not threw growing. Her second heat cycle will be 6 months after her first heat cycle.

Usually around 6-9 months of age,but in this time period she shouldn't be bred because she is very young,and you should wait until she is at lease 2 years of age for this.