how long from when we activate a sandbox refresh are we supposed to be able to login (its been like 30 minutes, and we have some scheduled scripts, that need to be shutdown.... which i wish netsuite would provide an option for disabling all schedules [search and script] for a sandbox refresh)

It should be available right away, definitely within 30 minutes

I tend to use

N/runtime

in my scripts (you can get the env type) to stop scheduled ones executing unless there's an override parameter on the script deployment

will probably need to do that