Yes that's correct. Two potential scenarios (assuming the SSW happens in March):

1) the winds on Feb 19 didn't reverse direction, but did in March, then the second major SSW onset is whatever day in March that it occurs.

2) the winds did reverse direction Feb 19 and then again in March. If less than 20 days passed between the reversals (which is likely), then the second SSW onset is Feb 19.

New post coming out shortly!