Why don't you make it so that your villagers/pigmen guys use the highest tool that you have? Or maybe have a locked worker upgrade until you get the tool? Because making diamond tools is a waste if your workers only use iron or stone.
Pro Tip: Do NOT work ahead, (I mean like go all the way to building traps and things) If you can't get the priest, DO NOT BUILD THE TRAPS. Also, it may be wise to stick with a stone pick for a bit, so you can build up some Iron.
Why don't you make a stronghold map, then you could do something with the stone bricks there, and the goal of the Stronghold place would be to build an end portal. idk
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workers do use the best tool in inventory. their graphic might not show that, tho.