Re-phrase the question. What are you trying to do and what is the other side expecting. DID is direct INWARD dialing. Then you say routed OUT the first channel. Doesn't make sense.
You can't control what channel an incoming call takes. Your PBX or PSTN provider does that. You also don't have a dial-peer voice pots that ties to the T1. The dial-peer voice VOIP doesn't do anything with voice T1's.
Do you want a certain call to go out the first channel of a T1 CAS?
Anyways, you might be able to set up two channel-groups in your controller t1. First channel group has one channel defined. The second has the other channels (2-24). The dial-peer voice xxx pots will send your call out the first channel group.