Should I apply Green card for my spouse and kid after I am a US

Should I apply Green card for my spouse and kid after I am a US citizen?

Currently I am a green card holder and long enough to apply for US citizenship.

The customs told me that I could apply for green card for my son and spouse now. Both my son and my spouse were born in Canada. I was wondering if the waiting list would be shorter

However I also heard that the waiting list is longer as a greencard holder sponsor so I was wondering if it is worth it to just wait until I get the US citizenship. Based on what I read, If I become a US citizen my son can automatically become a US citzien so I wasnt sure if I need to apply for Green card for him. Too much information just confuses me.

The citizenship application page said if your mum is a US citizen by birth or Naturalization before your 18th birthday you are already a US citizen. Is this true?

 

Thank you!