wont impact it during the upload. (or at least it shouldnt as long as you dont have some crazy bandwidth/cpu issues going on prior).
you'll have to issue the ASDM command to set the ASDM file. i believe after you do this, you have to bounce the box (not 100% sure, but I always have in the past) for the new asdm image/command to take effect. although i could be wrong about bouncing the box. so try to connect to the asdm before bouncing it and let me know.
-brad
www.ccbootcamp.com
(please rate the post!)