Just glancing at the wiki confirms what I thought I decided -- that the later you open them, the better the loot. While I didn't see it anywhere, my testing suggests gold crates' loot is independent of when you open them. I know of 6 reasonably accessible gold crates, and another couple that are more involved, and they always seem to all contain great seeds, and there is the initial lirma and three more seeds you can pick up without opening any crates and fixing their contents. Several more if you take a jaunt out to where that crazy guy started. Yes, you have to open some to get food until you can grow your own, and fabric for at least the agility boots(T1), but I'm starting to wonder whether early looting everything off the wrecks is a good strategy after all. The small containers, sure. The deconstructables, sure. The stuff just sitting there, sure. But maybe I'm better off waiting until lakes start forming. That doesn't take very long, and gives a lot better seeds, particularly mushrooms, which seems to be a bottleneck, at least for me.

What say you? When do you open the blue chests? And do you think the storage locker is independent of when it's opened? I've grabbed a rocket engine out of it once, and I'm pretty sure that was before it even started raining.

Please take all of this with a really huge grain of salt, since I am not familiar enough with Unity and (of course) do not have access to all of the projects' resources.

From first looks, it would seem, that every container that can spawn loot, regardless of it being a Blue Crate, a Gold Crate or a Locker Storage does so depending on three criteria:

1. A fixed set of items per individual container you will always find in that particular container
2. A fixed set of items per individual container, where the game rolls dice for whether or not to put any of these items into that particular container
3. A fixed Terraformation stage threshold value per individual container, which decides on yet another round of dice rolls for putting additional items into that particular container based on a fixed list of possible items per Terraformation stage

So you are right in assuming, that the Terraformation stage impacts what can spawn inside of a container. Alas, since containers can vastly differ in all three of the above criteria, in order to optimize yield, you'd need to know the exact criteria for each and every container in the game.

Apart from all my other rather cursorily guesswork: What if the game fills a containers' inventory the moment you see it (or are "close enough" to it), and then never regenerates that, even if you do not open it ? That may be checked by playing around with savegames, though.

Edit:
Being so busy with all the tech babble, I missed answering your question :)

No, I wouldn't delay opening containers, unless I knew what could spawn in them, if I waited, and could afford to wait.

Turns out the whole thing is a bit more involved. For instance, if you go to the shipwreck in the sand dunes too early, there is no [spoiler]rocket engine[/spoiler]. I have not yet determined if it spawns in later in the game even if you already explored the wreck. It may be you only get that if you wait until lakes. Additionally, there are seeds (mostly eggplant) in that wreck if you wait, but I have not yet verified that they spawn in later if you explore the wreck too early. And I could have sworn that waiting gave me more mushrooms and beans as placed items, not just eggplants. On the other hand, exploring on day 3 there are no seeds at all on the shelves. They might spawn in later. Not confirmed, though.

There are some things I think do spawn later, and some I think might not. I'm starting to think if you enter the wreck in the aluminum area, you might not get the later spawns, but I'm not sure when they show up, so the whole grain of salt thing.

The golden chests appear to be either fixed or at least determined at the create new map phase. Not exactly clear in the wiki, either. The two I generally open in the early game (day 1 or 2) don't seem to matter. If I leave one of them alone until the lakes phase, the same kinds of stuff are showing up, so those seem to not be worth waiting on. And the ones I leave until later seem to have more or less the same stuff the early ones did. I suppose I could verify through savegames, but I'm not that motivated.

The locker in the base near the dunes wreck seems to depend on when it is opened, or maybe when it is looked at, as you suggest. Not sure.

The hard and fast problem for a speedrun seems to be mushrooms. Bioplastic is way too important in the midgame to risk not getting enough mushroom seeds. So at least some of the crates have to be saved for later.

As a kind of related issue, is it worth taking down the T2 drills that are built in the lakes, or do you find they use so little power that who cares? Swapping out T1 for T2, sure. Until the ore miner, its pretty hard to come up with enough aluminum to upgrade everything to T3. Seems at that point in the game, the ore extractors pull more or less the right ratio of aluminum to iron and titanium for T3 anyway.