More on Hojo Soun and Izu province

I have been noticing that the dates for Hojo Soun's invasion of Izu
province is placed at either 1491 or 1493. 1491 makes sense because
that was the year of Chachamaru's violent grab for power and the
start of a civil war. But 1493 makes sense too because it was the
year that Jundouji's (the younger brother killed by Chachamaru) older
brother Ashikaga Yoshizumi took control as Shogun, and that would
have given Soun the 'justification' for invasion - to avenge the
mother and brother of the Shogun. Not to mention 2 years of civil
war in Izu would take a toll on everyone involved, given Soun an
easier time of it all.

So which is it, 1491 or 1493?