but you'll need to get posted to one of those units to get Jump qualifications.
You do not have to be in a third battalion to get a jump course.
Dizzyboxing, the Canadian equivalent to a Airborne Infantry Soldier is a Airborne Infantry Soldier. As for getting a spot for the jump couse in your contract, the US Army does that, the Canadian Forces does not.
As mentioned above by MilEME09, the Canadian Army only has 3 Regular Force Infantry Jump Companies. You do not get a choice as to which battalion you go to; some point during your DP1 Infantry course you will be told where you are headed.
If you get into a third battalion(Light), you may get sent straight into a jump coy and get your course quickly. OR, you may need to wait awhile to get the course and moved to the jump coy - if you even get that opportunity. As well, there are other units in the Canadian Forces that have a jump tasking/role.
If you are posted to a 1st or 2nd battalion(Mechanized) there is still the opportunity to get the course. You may get the course quickly, or years after getting into the battalion or not at all.