When you add a new employee at People > Add the form doesn't ask all the questions it could (e.g. whats the calendar, work pattern, phone numbers etc) and instead sets some of this info as it is instructed by the information at Admin > Settings > Your Defaults. 

If this info is going to be wrong (i.e. your adding a Ireland based employee and your default calendar is set as UK) then you will need to edit the employee slightly immediately after adding them (e.g. People > Employee name >  Person > Work).  Its good policy to check the details anyway even if you don't expect there to be any changes.

Once you are happy with their details you can release their Welcome Email at Admin > Settings > Email > Welcome Email.