This is a peripheral area to a game that adds depth and flavor, but often results in more confusion than it is worth.
Keep it simple.
I use a 12 month calendar with 30 days in each month. Each month is broken down into six weeks of 5 days each. The lunar cycle follows the cycle of the months, so there are always full moons on the night of the 29th, 30th and 1st and no moon on the night of the 15th.
The 5 days of the week are all named for things you find int he sky: Sun Day, Moon Day, Cloud Day, Star Day, Dark Day.
Each months is named in relation to the seasons. Early Spring, Full Spring, Late Spring, Early Summer, Full Summer, Later Summer, Early Fall, etc ....
As for years, many campaigns end up with a few dozen sets of dates. That is more of a hassle than it is worth. Pick a rather *huge* number and add two letters after it. For instance, "34,010 DT". When people ask what the DT stands for, say that nobody has any idea. I'd suggest keeping the last 3 digits as a low 3 digit number so that it is easier to rememeber for the players.
As for naming ages, that is really a product of your campaign history. Name them for Empires, technological (or magical) evolutions, etc ... In my High School Campaign (the last campaign where I used ages), I had the Dark Age, the Stone Ages, the Soft Metal Age, the Hard Metal Age, the Divine Age (when Divine beings started to meddle int he affairs of mankind), the Magic Age (when man mastered arcane magic), the Blood Age (when the BLood War spilled out onto the PMP and the world was left in ruins), the Ice Age (when a great freeze drove the demons and devils out) and the current age of that campaign - the Pheonix Age (when the ice had pulled back and the goodly races had restored new empires - about 1300 years old at the time of the campaign).