Wait lists for good daycares can be really long in some areas. We applied at our daycare when I was 9 weeks pregnant with #1 and we finally had placement when he was 10 months old.
What you're looking for really depends on what age you'll be starting and your own parenting style and a lot of that might even change when baby gets here and you learn their personality.
Mixed-age care is really beneficial if you can find it. The daycare we ended up at was a 0-3 age grouping and the mix allowed them to provide better quality of care all around, especially compared to infant rooms where too many babies have too many needs all at once and they usually can't provide the attention that infants deserve to have and the 3yr-only rooms with too many heads and big egos to provide quality activities and direct interaction. I tell people to look around the room and see how many baby "containers" are present at the facility they're considering. There should be a limit to how long a baby is left in a container all day rather than being held, exploring, or interacting with caregivers on the floor. If the room has a lot of containers (and especially if a lot of babies seem to be in them when you do a random drop-in for a 3rd or 4th visit), it's a sign that the babies aren't getting as much interaction and free exploration as they should. Do they hold and bond with the babies while feeding or do they feed the baby with the baby strapped into a bouncer/lounger/etc?
I would ask how they handle assisting children down for naps. I would stay longer than a few minutes and observe how they respond to infants crying and how quickly the crying is attended to. Do the caregivers seem overwhelmed or do they seem to have an appropriate number of caregivers to infants (and there will be legal limits, but the actual appropriate number will vary based on caregiver capabilities and the personalities of the children in the room)?
If you're going to breastfeed, how familiar are they with paced bottle feeding? Can they give a correct answer about the general average that a breastfed baby will eat during the day? If you see them interacting with older children, do they deal with difficult behavior in a way you're comfortable with?
How much do the children actually get interacted with and what is the quality of the interaction? I can't say with his first daycare that the caregivers actually spent time talking to the children or reading books with the older infants or actually getting down with them to play because they were too busy attending to the immediate needs of the room, which were many because it was an infant-only room.
How is continuity of care at the facility? Do they have a high teacher turnover? What's the likelihood that your child will have the same primary carer throughout their early years at the facility? Are the children with mostly the same people all day or do they cycle people in and out of the room in shifts so that they go through several groups of carers throughout the day. Continuity of care is very important to early childhood development.
There's a lot that you can consider when you're looking at daycares. It's a lot to digest. I would start now just to give yourselves time to think about the things that are important to you and to learn as much as you can about your options before making any decisions.