Our dummy foal last year was fed every 20 - 30 minutes for the first 24 hours, which was when she finally got it!
She drank from a bottle well and soon identified the bottle.
We then put the bottle thru from the back, between the mares back legs and with the nipple between the "real faucets". ... eventually she made a mistake and hooked on the the "real thing" while searching for the bottle nipple.
We milked the mare every 2 hours so we had enough to feed the baby every 20 to 30 minutes. p.m. me if you need more details.
It was almost right on the 24 hour time frame that baby figured it out.