Setting number of rings before answering for day vs. night

I see how to set up one IVR for day calls and another for night calls. Is there also a way to set the number of rings before answering, based on time of day? During the day we’d like the line to be answered after about 4 rings (or whatever number of seconds that comes to) but at night the line should be answered immediately. I would guess this would be in the configuration for each incoming route, but I don’t see it there. I don’t yet have a FreePBX system, and am relying on documentation and screenshots. I’m considering getting a PIKA WARP, which runs Asterisk 1.4 and FreePBX 2.5.

Well in FreePBX 2.8 it is very easy to set up an IVR for day and one for night calls.
Go to Inbound Call Control - Day/Night Control. There you can define an IVR for day and one for night.

[edit]
About your second question, the number of rings. I think you need to set a queue to an IVR and define this in the queue.