If you're exclusively breastfeeding or alternating, it's ideal to start ahead before baby starts daycare. Here are some tips.

Moms who are breastfeeding their babies often feel a bit of stress and anxiety about baby's feeding schedule when they start going to daycare.
Whether your baby is just a few months old, or approaching the toddler years, it's a good idea to prepare enough breast milk for their week.
Some mother's get a bit over-eager and feel as if they need to have a ton of milk on hand at all times.
Pumping too often can also increase your milk supply, so make sure that you aren't inadvertently causing a bigger issue for yourself!
The reality is that your baby will probably feed about as often as they do at home when at daycare, so you can monitor their feedings for a week or so to see how much, and for how long, they are feeding.
Get Into The Pumping Habit Before Daycare Starts
If you aren't used to pumping, and baby has always been breastfed, you will want to get into the habit of both pumping and bottle feeding before daycare starts.
Give your baby enough time to get used to this transition, as some babies are initially unhappy to switch over to a bottle.
You don't want the added stress that your baby might not eat at daycare because they aren't used to being bottle fed.
It might take you a week or two to understand how much you need to pump in order to fulfil your baby's daily and weekly milk supply, so get a head start to avoid any additional stress.
According to Pumping Mamas, starting to pump 2 to 4 weeks before daycare begins will also allow you to start a small freezer supply, which will mean no late-night pumping for the next day's supply.
Know Your Baby's Daily Intake
Once baby has been introduced to bottles (whether you are giving just breast milk in a bottle, or alternating with formula bottles) you can begin to monitor how many bottles they drink per day.
Since daycare hours will vary according to your schedule. you can estimate how much milk they will generally drink during the hours that they are away from you.
Send A Little More To Be Safe (But Not Too Much)
According to Kids Care, a breastfeeding mama will generally produce more milk in the morning, so this is a great time to pump any additional milk to have on hand. You will want to make sure that your baby has more than enough milk to drink while they are away from you, but don't send too much, either. Most breastfed babies drink about 1 oz. of milk per hour, according to Balanced Breastfeeding, The volume of milk consumed by breastfed babies is much lower than formula-fed babies, and changes very little even as they age. But this isn't set in stone, each baby is different.
If your baby drinks 2 oz. by all means send 2 oz. This is simply a guide, not the ultimate answer. Only you and your baby will know the perfect amount needed. Don't doubt your internal mommy radar; it's more attentive than you think. Make sure that you are clearly communicating your feeding requests and baby's schedule, and ask the daycare staff for regular updates to make sure everything is going smoothly.