Glad to see some fellow trekkers here. Been to Mt Kinabalu twice and it was a 50-50 for me: once it was foggy (and strong wind) at the summit (Dec), the other was a nice clear day (April). Here is my itinerary for your reference:
Day 1: Fly to Kota Kinabalu, transfer by bus to Mt Kinabalu Park HQ. Stay overnight.
Day 2: Leave extra belongings at Park HQ. Transfer to trail head (Mesilau which is the new trail, or Timpohon the old one). Climb up to Laban Rata. Stay overnight.
Day 3: Wake up at 2:30am and proceed up at 3am. Need to time according to your pace, as you don't want to reach the summit too early and expose in the freezing wind. Need to reach the summit before 6am to see the sunrise. Come back down to Laban Rata. (Note: acclimbatization is not necessary as the summit is only 4000m and you descend immediately after summiting.)
Now here there are 2 alternatives: for a longer and more relax trip, stay 1 more night at Laban Rata, and descend the next day. For a shorter but tougher trip, descend on the same day.
Day 3/4: Descend to Park HQ. Transfer to Kota Kinabalu and stay there overnight. Have a sumptious seafood dinner.
Day 4/5: Fly back to Singapore.
Oh ya, if you prefer you can also see some of my Mt Kinabalu travel pictures here.
For those who are thinking of going, go go go, it's a very nice place. Really.
Hope that helps, and have fun!