Generally, a spouse can petition the court for support at any time. Prior to the filing of the Complaint for Divorce, a spouse can file for spousal support. After the Complaint has been filed but before the divorce is final, a spouse can file for pendente lite support (which is just another way of saying temporary support) which can include child support. When you reach an agreement and enter into a settlement agreement, then you define the terms of alimony which typically go into effect once the divorce is finalized.
DISCLAIMER: Please be advised that this is general information for informational purposes only and does not constitute legal advice, nor does it create an attorney-client relationship. It is strongly advised that you contact a local attorney to obtain legal advice specific to your case.