How long will it take to cover the premolar extracted gaps with invisalign? (4 teeth are removed). (photos)

My premolars are extracted long back. I used ceramic braces for 1 year. The gaps aren't closed. It's almost a tooth gap but my teeth went back. I removed ceramic braces due transfers. Can I use invisalign now?? If I use that how will it take to cover these gaps? I am 21 years old and initially I have teeth looks like height(front) so they removed my 4teeth to wear ceramic clip and adjust through the process.

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