H4 stamping for 3 months

My H1b is valid till 1st of October. I am planning to send my wife for H4 visa interview. Meanwhile my employer has filed h1b extension which i got an RFE and i am not sure, when i will get that approved even though it is applied through premium processing. Can my wife go for H4 visa stamping for 3 months?

Your response will be appreciated.