Growth spurts

Kayla • Married & we had our perfect baby boy on 03/21/2015, Pierce Huntlee. He was 7lbs 10oz, & 19.5 in 💙
When did you guys notice your babies first growth spurt? My little one is 10 days old and the past two days all he's done is eat. I'm trying to figure out if I'm not producing enough or if he's in a growth spurt, not sure if they can have them this early?? Thanks!