Tried a dummy booking and did not work (did not get the first 4 rows). Also called the Summit hotline and they told me at check in (24 hours ahead).
I don't really like it this much and the last 2 flights on flight 1 the online option did not work or all seats were taken and on the next one I got a seat when checking in online but then looking around I had the distinct feeling that most people were actually ones checking in late (talking to seat neighbors).
I think this whole system does not work well for elites. Maybe over time it sorts itself out but up to now I am not impressed at all. Also I hated the 24 hour Southwest game with a passion and now with stretch seating I seem to be back playing it if I want a seat up front.
Also in reality it is exactly 6 seats that I can choose from since I want isle non bulkhead.