Is it possible to have H4 stamping just with H1B extension approved?

Hi,

I have received my H1B extension copy approved but haven’t applied for my wife(H4) and son’s(H4) extension until last month. And we planned stamping on Dec 3rd Week in Canada as our Visas are still valid till 31st dec.

Now the receipt of H4(I-539) is still showing as received. Will it be approved within 2 months? What if we go for stamping with my I-797, will they stamp on my wife’s and son’s passports as they are dependents?

Kindly advice