Pumping and Breastfeeding

I pumped my son's first 5 weeks. And then went breastfeeding. And have been bf minus occasionally getting a baggy of milk. But I'd like to start getting a feed a day for dad to feed him (still takes a bottle like a champ) when would be a good time to do so? And should I do it more than once a day? I feed on demand, sleep on demand. So not a super great time schedule. But anything helps! Thank you! Oh! And he eats about..... 3.5 to 4oz a feed I'd say? My last lump (10 mins ago) yielded 2.5oz and he was still hungry so that's my guess. He's 99th height and 99th weight%. Thank you for y'all's time.