Definitely put in early (consider those fees to hold a slot insurance) and visit the places. Visit at different times/more than once if you need to. The center my husband and I chose we both visited before we accepted the slot. We had two slots available in our timeframe, but before she actually had to go to daycare, another place called and had a sudden opening. Don't let the 9-12 mo. wait list scare you.
I had good luck asking my coworkers where they sent their kids and if they would recommend anywhere/not recommend anywhere.
And don't just look at the bottom line. We turned down a situation that would have been cheaper, but we didn't feel entirely comfortable. Friends of ours have an offer from a neighbor, but they can't stand her kids' behavior. I suggested that they keep looking. If she can't control HER kids, what will happen to theirs? Ask for references. Look around at the facility - not just where your baby will be but where baby will be later if it's a daycare center. Are the other kids happy? How do the staff react to their needs? Does ANYTHING set off your radar? Trust your instincts.
What is important to you? I wanted my baby to develop a schedule, not be forced into one. A center that let her be herself was important to me. Her center is in a church - which suits me fine, but maybe wouldn't suit you. I like that it's a good mix - they listen to holiday carols as well as "Jingle Bells" around Christmas. If we stay there through preschool, they have a program that gets kids ready for MCPS kindergarden requirements.
A good place is immeasurable. I don't always like to drop off my baby, but I know she's somewhere where she's happy, loved, and safe. That helps a lot. I can drop in anytime, or call, and I never have a problem. I also like that while she's in a center, it's homey and her class isn't huge. Max is 6 babies.
Good luck!