how long should I wait for a message or should I message him first?

[Pixie]

I work at a sales assistant in a shop in a hospital and one of the cleaners in the hospital comes I'm every time I'm working and tries to flirt with me.

after about 2 months he's asked for my twitter and we are now following each other on twitter as of lunch time today.

how comes he hasn't messaged me yet? I want to speak to him to get to know him because I know nothing about him but I feel like he should message me first?

what should I do, I'm next in work on Sunday and I know I will see him then and I feel like it'll be awkward when I see him on Sunday if we haven't spoken on twitter in between now and them because that's obviously why he wanted my twitter?