I can't contribute any data points from my own 04A, as I bought it with FW rollers all round, but from my research several years ago, late January dates (26th, 27th and 28th) were what I determined likely for that build timeframe at Van Nuys.
The fact that there are those 3 consecutive dates, as well as mid-January dates, suggests that Kelsey-Hayes ran off a large number of YH wheels which probably kept both plants stocked for quite a time. IIRC, there was another run at the end of February but nothing in March, until the next batch in April. I originally figured late Jan or Feb would be OK, but didn't come across any late March/early April VN cars with the Feb date.