Hi Ashton,
I medicated mine and then fed the next night. Obviously they aren't going to want to eat after you medicate them, and I wouldn't medicate after feeding b/c they may regurge it. Mine ate just fine the next day, and they're been doing excellent ever since. But as far as letting the meds take effect, I wouldn't worry about time span in between medicating and feeding. Good luck!!!
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Currently keeping:
Geckos:
Eublepharis macularius (various morphs), Paroedura picta (banded, stripe, and amel), Paroedura bastardi bastardi, Paroedura androyensis, Hemitheconyx caudicinctus, Rhacodactylus ciliatus, Cyrtodactylus irianjayensis, Gekko gecko, Pachydactylus turneri, Uroplatus henkeli, Teratolepis fasciata, and Oedura monilis.
Snakes:
Corns, a single ball python, a pair of Taiwan Beauties, and a pair of Tangerine Honduran Milks