Help!

My son is 3 weeks old. I want to try to put him on a schedule, but he is a very colicky/ high maintenance boy so it’s making it difficult... he’s good for my husband..once my husband leaves he pipes up..😡 just this morning he was up at 3 to eat, cried until 4:30, slept from 4:45-6:20, ate at 6:30 and has been fussing since then (except for when I feed him). It is now 11:50 and he’s only taken a 30 min nap.. what can I do to get him to nap more during the morning and get him less fussy? It wouldn’t be so bad if I didn’t have an 18month old at home who also needs my attention.