Armholes for a poncho

Just knitted a lovely poncho for my daughter in law but now realise it would have been better to have knitted with slits for arms, is it easy enough to add these and how as thinking of unpicking to add them in, poncho was knitted on circular needles?

Can you give us a link or a pattern name please? Was the poncho knit bottom up?

The pattern is called Octavia Poncho by Grace Rose Designs if that helps?

Very pretty!
https://www.ravelry.com/patterns/library/octavia-cable-poncho

You could either cut the knit fabric (steeking) or you could rip out the lower portion. Since it’s top down, ripping out the lower portion wouldn’t be too painful. Usually slits are about a elbow level.
If you’d like to steek, here’s a video to give your an idea of how it works. You’d have to pick up sts around the slits to make a hem or border.