What is the average time to have expander in upper jaw?

Depends: The expander is used to widen the palate and maxillary arch to accommodate tooth alignment. The time varies due to the room necessary. Discuss with your dentist.

6-9 months: The exact amount of time is related to the specific treatment. Generally younger patients respond faster.

Younger, the better: commonly, we will use expanders while kids are very young-- 7 to 13. The effectiveness begin to reduce as the bones in the upper jaw begin to fuse. That said, we have had surprisingly great results with some patients as late as their early to mid 20's