You can agree on a parenting agreement any time you like but a parenting order (which is legally binding) goes through the courts so I would imagine that if you needed one that would have to wait for a while.
We separated when my daughter was 5 weeks old so the parenting agreement I drew up might be useful to look at. I used the Family Court one as a guideline and although it seemed that a few of the issues were a long way off he has already attempted to re-neg on one financial issue that came up so it has been useful to have it.
If you want mine to have a look at just PM me and I will send it through.