Custody/child support

Normally, child support is decided during separation. As in, “I’ll pay you $x a week for the kids”. But if you have a custody arrangement and neither party is looking at changing then child support can be determined using that arrangement. Mediation is mandatory but I believe that it’s best use is when custody can not be agreed on. I think that you can ask for a continuance on this, but that would depend on whether one of you has filed for custody…

What comes first? I am wondering because my stbx and I only have an ex parte order and nothing has been said about mediation, yet we are having a child support hearing next week (see Imputing income thread). Shouldn’t child support be decided afterward? Could I ask for a continuance from the judge until atleast custody is determined?