After some more research.....
I don't know if this link works.... but I see 3 trains departing between 7 and 8 am that can take you to Mineola from Ronkonkoma in roughly 45 mins....
MTA LIRR - Schedules & Fares
From Mineola your best bet seems like N22, N78 or N79... all of those go to Roosevelt mall. I don't know how long it takes and how frequently the buses ply.
It seems like westbury is more of a pain as it usually needs a transfer.
Please verify the info with LIRR anyway, I just picked this from their website.