How to get feedback on a paper most effectively
The answer is really &quot;it depends&quot;.
What kind of feedback do you need? If you're worried about the overall structure and the correctness of the results, sooner is better, but don't make your reader struggle with fragmentary work. Make your best guesses, write a draft, and provide marginal questions (&quot;do I need more detail here?&quot;, &quot;should this section be omitted, or merged with an earlier one?&quot;).
If you're comfortable with your second or fourth draft and want just polishing, send the paper when you think you are nearly finished.
If you know the potential reader well enough you might ask what kind of feedback they are willing to provide.