just open them as you need them for gold imo
#How many crates should I open and save after 99 Wintertodt?
knotty geyser
only thing i specifically waited for was 60 wc for magic logs for dt
there will be a small difference in what you get of course yeah, but i think slightly worse loot early game will be infinitely more helpful progression wise than slightly better loot later on when you don't really need it anymore
pulsar pendant
I just opened them all after getting 60wc
the better rewards don't matter much at all imo, you just want as much gp as possible to save time blackjacking
obsidian delta
Repeating what other's have said: open as soon as you have some use for the rewards, gp mainly but also resources such as logs for birdhouses, quests, jewellery for transportation. I don't believes the rewards improve meaningfully by waiting other than 50+ wc for magic logs for quests. Even magic logs you can just get the level since it's needed for diaries later. most everything else is easier to aquire later and you just want to get there smoothly.