I suggest you call each carrier involved and ask them what their "ticket time limit" is.
Your travel agent should see the messages sent by each carrier in the PNR.
Each carrier is different.
It is best to ticket before the "closest" ticket time limit.
Always keep in mind that irrespective of what the "advanced purchase requirement" is, the ticket time limit may be different.
Based on my experience, when I book directly with CX, I always ask them to "enter" a ticket time limit that is inline with the advanced purchase requirement for OWE fares. However, they warned me that other carriers on the itinerary can still choose to have different ticket time limits.