Mom brings minor child

[PhiLandShiR 18]

Hello Everyone,

My wife is just finishing with her Removal of Conditions. I expect she will get her new 10 year Green Card in a few months. We just completed her bio-metrics.

She wants to apply for USC ASAP after she gets her new GC.

On the N-400, Part 2, it states she can apply for USC after she hits her 3 year mark as a Legal Permanent Resident.

SO...

Question ONE, what date is used to start the count on the 3 year time period?

After she gets her US Citzenship, she wants to bring her mother over here.

Question TWO, how long does it take for a petition to bring her mother to complete?

After her mother arrives, her mother wants to bring her child here. Her child is my wife's younger sister.

Question THREE, how long does it take for her mothers, child petition to complete?

The reason for these questions is that my wife's younger sister just turned 18 years old, she is not married. If she turns 21 years old or gets married, she can no longer be petitioned by her mother.

SO...

Question FOUR, can all of these steps be completed in the next 3 years? Or are we just wishfull thinking??

Question FIVE, does the clock stop after the papers are filed for the mothers child? She could turn 21 and still get a visa?

Thanks!!

Phil