Japan also invaded the DEI from British territory that they seized in their initial attack.
I think that the Japanese were somewhat correct in their logic to try and wipe the British and Americans out of the area first, anything else just exposed their flanks and made them super vulnerable.
Japan did not even bother to announce a DoW against the Dutch until January 1942. They sent a letter of demands and ultimatum, but other wise waite over a month.
Is some other sort of play here by Japan, some sort of coup or sponsored rebellion in the DEI? Complicate things by spinning some hypocritocal yarn about anti imperialism or pan-Asiaism (a thin premise I admit, given their very public atrocities in China) and backing some Indonesian rebels? Though I imagine that is too long a time to enact with the current embargoes/probably would invite Allied retaliation or counter involvement.
There was unrest, but the Dutch & locals on their side had a handle on it.