Like Text Messages!
I'm sure DD1 will be fine,to be honest although my DD1 mentioned the odd name a few times,I still think they are too young to have "proper" friendships.She also asked to be in the same class as this one person she would mention occasionally.
During the summer she received a letter from her new Teacher to be with photographs (lovely idea,I hope they still do it) saying that she was looking forward to meeting her.
I kept practicing the name with her,and then on the day she started we found that she was in the other Reception Class,and not with her "friend"!!
I can only suppose they had to a bit of last minute juggling due to the extra 10 places they'd been granted.
So all of her class were "familiar" but she had no "close" friends.But because they start with just a small batch,these became her first friends.Its taken a whole (school) year for her to be friends with most of her class.Even the shyest,quietest children have all settled in well,and have their circle of friends now.
The Birthday parties help,so prepare yourself for the "Adventureland" parties with 10-20 children!!
Howabout inviting a mum that you chat with,and your DD knows,over.Much easier to break the ice in your own territory IMO.
Panic not, SP this will all be "old hat" in a year.