That seems too long, but I don't know just how small the bedroom is, nor how cold it is outside. Both would affect heating times. Also, heating up a well insulated room is very different from trying to heat a space that doesn't hold the heat inside. So for instance, single-pane windows are going to allow heat to escape, whereas the newer double or triple pane do a better job of insulating.

I've used oil filled radiators because they don't bother my asthma.