How long do you have to separate a cria at weaning

[Farmer Jim]

I separated my male and female cria 3 weeks ago and after 2 weeks of separation I brought the female back in the girls pen. I thought all was well but at feeding last night I noticed that after eating the female cria was sucking from her mother. I brought the mother in and she still has milk. I then separated the cria again but how long does it take for the mothers milk to go away. The mother is pregnant and due in Aug

Thanks

 

[ksalvagno]

It should only take a couple weeks but it was suggested to me to keep them separated for at least a month.