how long to labour for a cervix 3cm dilated without contractions.

Doc says my cervix is 3cm dilated at week 35 during check up, gave me 2 jabs to speed up the baby's lung development as well as pills to prevent contraction. How long can I last till labour? I do not feel any contractions at all, everything seems pretty normal for me. Doc told me to bedrest until week 37 for a full term baby. Anyone have the similar experience? First time mum here.