What's a good early age to put your baby into daycare?

my daughter has been going to nursery since she was 6 months old and she loved it, ive never had any problems, no seperation problems, she spent a week settling in before she started so she got to know the girls before she started. She has always been well cared for, she loved being around other children when she was a baby and has grew up with them throught she is now 5. I worried about my daughter being away from me when i was at work but she was fine and always having fun. My son is starting the same nursery in september,he will be almost 7 months by then.