Putting a Mare back in foal - when to scan?

[winchester]

Hello - please excuse me but this is still very new to me!

My mare had her foal on Sunday 10th May and i am going to put her back in foal again! Vet said he should scan her on 24th day after the foal is born - which will be Wednesday 3rd June - is this right?

 

[rsc]

We work on 28 days post foaling and they usually get covered around 30 plus.