As many others have already stated, for me it is about what responsibilities you have after said beer(s). If you can have 1 or 2 and still handle those responsibilities then go for it...if you have nothing to tend to then knock yourself out and drink til your hearts content (although I would suggest you still keep in mind health concerns associated with habitually over drinking).
As far as time of day I see it having no bearing on the situation whatsoever. I like coffee, but honestly I am one of those guys that prefer a cold soda (if beer is not available) over a hot beverage in the morning with breakfast. Also, I tend to enjoy lunch/dinner food over traditional breakfast food in the morning. When the fellas would hit a diner in the AM after a night of partying, I would be the one ordering a cheesesteak or a big ole juicy burger and fries with a soda....is there anything wrong with eating those foods for breakfast?....who says you have to have eggs, bacon, or flapjacks? Likewise, who says you have to wait for a specific time to enjoy a brew? Regardless of your schedule or shift, I say have a drink whenever you want to have a drink and (as others have also stated) as long as it is not negatively affecting your life then sit back, relax, and enjoy!