Connect OVH email service to shopify domain

Hi,
I have an ovh email service that and I am trying to add an associated domain from shopify. It has asked me to create a CNAME record in shopify DNS settings which I have done (pointing to ovh.com).
From what I have read it says that you have to wait 24h - 48h for it to take effect but it's been longer now and still nothing happened. Is there anything else that is required to be done in the shopify DNS settings or is it just the case of waiting? do we receive an email to confirm?

Thanks in advance for any assitance.

!image|690x78