Originally Posted by YYT82

You can try checking in at 24 hours before your next non-checked-in flight, or you can have the agent at the airport checking you in for all segments and get your boarding passes.

As for standing by early, you can do it through OLCI but only for your business class flights, or if your economy class flights fares allow early standby, or if they are Rapidair/Western Triangle/YYZ-NYC.