Hi,

When there is an online open call, do the casting directors usually wait until they have received and viewed all the submissions to start callbacks or do they contact actors as they see their submissions?

there are no steadfast rules in this business. don't expect a hard answer for anything. each person in each position (from actor to director to agent to casting director to 'the client' etc) will do things completely differently from each other.

my advice?

don't wait by the phone. and if they call, all the better! some may call immediately, some may call the next day, the next week, or 6 months later. don't wait by the phone. you'll miss other opportunities. or be really upset and disappointed if they don't call, which, lets face it, is quite likely in this industry for us all.

but it's not considered a "callback" unless you've already auditioned and they call you back in, hence the term "callback". so really, you are just waiting for them to call you at all. after you audition the first time, if they call you again for the same project, THAT is a callback.

hope this helps!