There are services that lets you schedule your Twitter messages. By using them you can tweet pre-written announcements or may appear to never sleep and you can invent many more creative uses of it.
Send it at a specific time in the future or send a reoccurring Tweet any time! By using it you can prevent forgetting the birthdays of your beloved Twitter friends again! Just schedule a nice Tweet on their birthday. Send status updates to Twitter even when your away from your phone or computer!
Following are the tools: