Editing 3000 words can be a time-consuming task, and it will depend on the type and quality of writing you have. If you have a simple copy-editing job which involves correcting spelling, grammar, formatting, and other basic aspects, you can expect to take from 4 to 6 hours. However, if you were doing detailed editing, such as rewriting and restyling, this may require 8 hours or more.
Regardless, it is important to give yourself enough time to edit properly, making sure that all your changes are consistent and thorough. Don't rush this process, as errors may slip through and slip past you. Do several rounds of edits, making sure that each one is comprehensive and that you are satisfied with the result.