30 days if served personally, 35 days if served by mail.
Litigation isn't for amateurs. and many cases can be decided during discovery if it's not done properly, so consider hiring a lawyer, at least on a limited representation basis so you have someone to run documents by to get some professional feedback.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.
I agree with the previous lawyer responses. There is more than just a deadline that you need to know to properly answer these forms of discovery. And, on top of it all, your responses can be used to get you sanctioned if you did them improperly. Your responses (or failure to respond) can also be used to get a judgment against you without the need for trial. Get a lawyer now, one with experience in the particular area of law. I have been representing consumers for 17 years against debt collectors. Please view my contact information and experience on my Avvo profile.