Here are rough ideas of the onset and end time of icing.
Surface temperatures will of course be key as the precipitation approaches this evening.
Here's where we are now. As you can see, we've already got temperatures near or below 30 basically north of I-70 and the ridges of North Central WV which is not coincidentally where most of the freezing rain is expected.
Note that from the Pittsburgh metro on south, the period of freezing rain is currently forecast to be fairly brief. Further north and east (where southeast flow will allow surface cold air to linger longer), a longer period of ice accretion is expected.