If milk doesn't come in

Hi Mommies. Question lang po, what should i give baby if my milk doesn't come in right away? I heard usually daw dadating after 2 to 4 days pa. And yes I've read about the rule on supply and demand na dapat mag "unli latch" lang. But ano paiinumin kay baby from day 1 to 4 before milk comes in? Enough na ba ang colostrum lang? Thanks