Despite your best efforts during the analysis and research steps, you will still encounter problems when you actually start your first draft. You can wait to address these issues until you have finished your first draft. If a word does not come to mind, you might simply leave that word in the source language, plan to return to it later, and continue to write freely.
When you get to the end of your draft, you can go back and look at the problem areas. This time around, the right word might just come to you, or you might have to do more research to find a solution.
Now it's time to take a break! A little distance from the text will prove helpful before you begin to edit.