hi-hope you can help-

i have a united biz flight from narita,japan to hnl arriving 640am..
i fly out of OGG same day at 9.55pm ..
i am going to buy a tkt from hnl to ogg but was wondering what would be the time i should book it for?
is a 855am flight too early? i will have one bag-will it take longer due to there being separate tkts?
regarding the baggage-presume i will have to pay for it on the hawaiin flight?prob not beneficial but am united 1k
thanks in advance