To put a little more meat on the bone, all 'full course' Category Freezes (aka Seat Locks) are 2 years, including for New Hires. Also, we call the 757/767 category "7ER".

However, after 1 year, you can be awarded a change in equipment to another base if you are unable to be awarded that new base in your current equipment in a given posting. The balance of your existing category freeze will be added to the category freeze resulting from the new position award. For example, let's say you get the 220 in indoc (which is not based in LAX or ATL), you can break the seat lock after 1 year to go to the 7ER in LAX or ATL, but you would not be able to go to the 7ER in NYC because the 220 is already in NYC and is junior enough to hold it. Also, since the 73 and 320 are in every base, if you get that in indoc you almost ceartainly won't be able to break the seat lock until 2 years (unless somehow, your seniority could not hold a specific base on the 73/320 at 1 year. But since the plug in every base on the 73/320 has been here less than a year, you are very likely able to be awarded the simple base change). You can change bases on the same equipment at any time availability and seniority allows.

SO, if you are desperate to get the 7ER category after 1 year instead of 2, you might consider bidding the 220 or 717. Just realize you effectively have to change bases to somewhere the 220 or 717 is not based in order to do that.

Also, keep in mind the time from award to conversion can be an additional 2-3-4 months, meaning in most cases you effectively will be stuck in your original category for 15ish months minimum.