there should be a time line / dungeon chart

[Lambdafish]

It is weird that you can encounter edda in POTD before ever doing tam tara hm... kinda like what happens when you level drg after completing HW...

That's because Tam Tara HM and lvl 50 DRG quest are from ARR, and HW MSQ and POTD are in Heavensward, there is a major time-skip between the two. The way we currently have it is the only way we can reintroduce previously seen characters from other pieces of content while also keeping story progression flowing (and preventing gating).

To the OP: If you want to do things in order, then just follow all of the patch notes, doing the content from each patch in order, because that is how the timeline works. Having said that, there aren't many instances where events from ARR create time skips against the rest of ARR content, the major change comes between expansions.