When is the best time to get permission for putting others figures in the paper? (Conference vs. Journal) My basic question is, should I get copyright permission for a figure before submitting a paper?

However I realize there may be two different situations, and I'm not sure if they are different.  


Should I get permission from original authors/journals before sending a paper for review or;
should I wait to get accepted and then ask for permission.


It seems to me that I should not waste peoples time for permission without being accepted first, but maybe the paper is stronger with figures.  For example, an image of a machine that the paper points out aesthetic features. 

On the other hand, it seems to me bad to submit a manuscript or paper and after submission finding out there is no permission to use the figure or image, and taking it out of the paper after being accepted.
It is good to ask permission from the publisher before submitting, even if the figure is from your own paper that was published in the past.