Topic: Chrono Trigger

Is there a specific timeline to follow or can one drop in and out of different times randomly and discovering/defeating what is there?

No, as with most RPG's, you can explore anywhere. As long as you have visited the time, you can go back. Once you have the Epoch, you can easily travel anywhere. By the way, there are many endings, depends on when you beat the end boss. Check the sparkling bucket at the end of time.

some events won't trigger, though, unless you've already fully completed things in a different time period. if something sounds odd, try visiting that same area in a different time period to see if there's something you forgot to do or someone you forgot to talk to.

There is an order of events to follow, but once you get to the "End of Time" area, you can go to the bucket and fight the final boss at any time.

Exactly! But I highly recommend fighting Lavos any time after you finish New Game + the first time. A perk about New Game + is that all difficulty will be depleted, and most of the endings is acquired through this game mode.
Either way, Chrono Trigger for the DS is awesome! One of the greatest turn-based RPGs ever made!!