Totally agree with Jon here...
In my car it normally takes about 5 mins or so so the coolant temp needle to get up to halfway (90C). This is with normal town driving from cold and in normal weather.
Recently with it being so cold it can take up to twice as long for the temp needle to get up to 90 - that's pretty normal.
Even when the needle has come up though I tend to give it another 5 mins or so before I use the power available just to make sure the oil is nicely warmed through. Of course, without an oil temp gauge its all guess work, but common sense would tell you that oil would take a fair bit longer to warm up than the coolant.
You can normally feel that the car becomes a lot more reponsive and smooth as it warms through anyway
J