You also need to figure out which recipes give you the most xp for your essences.
Tipically you'll only craft 2-3 of a chosen shard before refreshing the window and moving on the next best shard.
As for amounts, the way the shards are tiered you can have a goal of advancing 10 levels at a time or something alike.
Otherwise you won't see the gain, e.g. going from +2 to +3 enhancement bonus.
For this you'll need a fairly large stack of each essence to be worth your time in the devices.
The body essence is the most common, so if you have a stack of like 1000 lesser body essences chances are you have a varied bunch of all the other essences.
The first time i did this went from 0 to 20, and the second time from 20 to 30, and expect a steep curve to go further.
A good goal for a lowbie would be reaching lv 40 to be able to make lv 50 recipes at 60% and make +4 items.
So you won't have enough craft for a greater bane but maybe can make a holy of pg or regular bane.
The prefix-suffix combos make decent mid lv gear (e.g. +6 modifier would be min lv 11).
At this point you move onto the mid levels and can begin to use named loot, gs, or buy the +5 gear from the AH.