If you don't mind using a glitch you can get this in the tutorial in about 10 minutes. Start a new tutorial world, go to the beacon in town. The chest has 5 iron ingots in it, take those and make an iron pickaxe then mine all of the emerald blocks under the beacon.
The glitch is very simple, have the emerald blocks in your quickbar, open the chest and pause the game at the same time, you should have the pause menu up and the chest should be open on the screen behind it. When you unpause the chest should remain open, press O and drop all the emerald blocks, they are going to drop but not reduce the number in your inventory. Open your crafting menu and reduce the emerald blocks to regular emeralds then close the crafting menu. Pick up the blocks you dropped and use a crafting table to turn the emeralds back into blocks. Just repeat about 3 or 4 times to have enough blocks.