For big classes you can have 2-3 people do an intro every day. Limit to 5 sentences or so. It's a good way to get to know everyone a little better.
For the first day you could do yours (obviously) and then ask for volunteers. There are usually a few brave ones in the class. fter that just do it alphabetically.
I do that with my elementary students -
- Hello how are you today?
- What day is it today?
- What is today's date?
- What's the weather like?
- What time is it?
For kids I always give some points, which is a great motivational factor!