Am I hurting my child by putting her in daycare at 22 months?

I was all excited to get a spot at our neighbourhood daycare centre
for my 22-month old, who has been at home until now, but a naysayer
relative has made me wonder if I'm hurting my daughter more than doing
her good by putting her in daycare at this age, in winter, no less.

I know my daughter will benefit tremendously from being around other
children in a structured educational setting. She will be in a group
of 9 children, who are looked after by 2 teachers and one part-time
assistant.

I work full-time from home, and have a 9-month old here as well. He
will stay with me until he gets a spot at the daycare at 12 months.

The relative (whose neck I would love to wring right now) insists a
child should be kept at home until age 3.

I am doing this because I need to keep my job. Until now I had help
from my mother, but she leaves in a few days, after having been with
us for six months. Already a huge luxury!

What I'd love is to hear some positive stories, and if there's any
scientific backing to my relative's claims.