Robbin asks a very tricky question: how long should you wait before you follow up with people who you've given your script to?
Eep. It's like dating...when is too soon to call? Too late? Surely there is an official rule etched somewhere in a dark cave that you will never find. I think you have to kind of balance how busy and important your reader is. Studio execs who work 12 hour days and take home seven scripts to read probably don't have time to learn their kids' favorite colors, much less read extra scripts. First off, if you manage to form a relationship with an agent, studio exec, producer, working writer, etc., you probably want to let them offer to read your script. To this end, I find that talking really passionately about what you're working on - and having those projects sound really interesting, unique and commercial - is a good way to get them to offer. Once they've got the script, give them at least a few weeks. Maybe more. It is okay to check in, but don't be pushy. And be prepared for negative notes. If you think it might help, reassure them that you're ready to be ripped apart. If it will push them along. And if you are indeed ready.
If your script is being read by someone lower-level, an assistant, an aspiring writer friend, etc., I wouldn't be so concerned about waiting a certain time to check in. Still though, even with people who are equally "important" to you, be polite. The relationship should go both ways. They're doing a favor for you - what are you doing for them? Also remember that lots of assistants have huge piles of scripts to read for bosses who haven't read anything since the other WGA strike. Sometimes people just get kinda swamped. I myself have a few scripts I've been holding on to for a little too long. But there's that pesky 40-hour-a-week job and going to the gym and reading books and writing scripts and blogging and watching TV and seeing movies and doing dishes and networking and the fact that sometimes I do none of these things because all I can do is get through the day.
If you try a couple times and get nothin from your reader, move on. If you've got some talent and you give it time, you'll find another way in. Your career will power on without them.
And if you're talking about query letters you've sent out, I don't think you're supposed to follow up unless they've gotten back to you and asked for your script. If they don't respond to your query at all, that means they a) don't accept queries, b) don't want to read your script, or c) both. If they did ask you to send it, and you did but haven't heard back, I think a few weeks is fairly standard.