I'm a KKH subsidized patient. Can I choose ward class B1(4 bed)? And when do we need to book? #ftm

I'm 35 weeks pregnant and my husband and I are discussing which ward I wanted. I'm a subsidized patient at KKH and I want B1 (4 bedder ward). Is it possible? Also when do we need to book? Or book when admitted? Please advise. First time mom here 🤗