When we had dd (just turned 3) we thought we were lucky to have a local friend who did childminding and she had dd from 5 months to 12 months or so. Then she had a third child of her own and we had to find a local nursery as she was struggling with numbers
Cm did a great job and we were concerned about nursery but it was the best thing we could have done, she's really benefitted from more children her age around
For various reasons when ds (now 10 months) arrived. We needed to put him in at 3 months and we were a little concerned this was too early, but again they have been fantastic.
Maybe we got lucky with the nursery (was also the only one we visited although we had options, just got a very good feeling about the place)
In a strange way (and this is just my perception so might be wrong and I don't want to paint a picture that nursery staff have 'favourites') there seems to have been a benefit from dd being there longer than most of the other children, seems to have a better, more natural, bond with the staff than some of the other children.
That being said we are lucky that both DP and I can work 3.5 days a week so kids are only in nursery 2-3 days a week and we get the best of both worlds. Wouldn't want to send youngest to nursery 5 days a week (although appreciate this is unavoidable for some)
What I would say is don't beat yourself up about it. If you have the right nursery there isnt 'too soon'
DD has a wail of a time in the week when either of mum and dad are at home but she still shouts 'yay, nursery we're here' every day we get there