My suggestions: compartmentalize setting up the work environment - here: put notes on table, open file, etc. - and the actual work. Basically you set up everything you need, then get a tea and then start work. That way the setup is not perceived as real work. Against ugh a timer might work. Commit yourself to work on ONE of the papers for 30 min, then a break, and if you are in flow then another round. But first just spend the whole 30 min on the paper. Regardless of what comes out of it. Overcoming the startup hump is sometimes enough to get going.

If your editing process is more complicated, then write the steps up upfront, and do them one after the other in blocks of time(s)