You have a few options available but there is no guarantee that the flights you want will definitely open up.

First off, I'll caution you about points.com. While it can be useful in some scenarios those are generally quite limited and the costs to use it frequently make the value proposition very hard to justify in many cases.

Next, CO (and I'm pretty sure UA as well) will allow you to book one itinerary and waitlist an alternate. Because award seats can be so hard to come by this is often better than just checking every day. Essentially they do the checking for you and you've still got the "bad" flights which are better than no flights at all. Of course, this assumes you have enough points to actually book the flights in the first place.

It is also important to know that CO only gives you three days from when you make the booking until you have to ticket it if you do not have enough points in your account at the time of booking. So unless you can make the points.com exchange very quickly you're going to have trouble anyways.

Finally, keep an eye on all the gateways that can get you to GCM, not just the CO flights. Partners can be very useful in award itineraries.