That is not the proper way to make a lager (and throw the instruction WL or WY give you away, they are a joke). You must start with the proper amount of yeast. For 5 gallons of a 1.052 beer 2 vials/smack packs in a 1 gallon starter would not be too big (ferment to completion, decant spent starter wort, pitch only yeast). See the pitching calc. at www.mrmalty.com
to get an idea what size starter you need for any beer, (be sure to use the lager "pull down" menu). Before you pitch your yeast you lower the temp of the wort down to about 4 degrees below your intended fermentation temp. So if you fermentation temp is 50 you should cool down to 44. Aerate 2Xs longer than ale and pitch your yeast. If you want to speed up the process and insure proper attenuation warm the temp up to 56-58 near the end of fermentation.
You never want to pitch a lager warm, ever, because not only will lowering the temp down to the proper fermentation temps kick up diacetyl, it also produces unwanted, unlager-like esters in your beer. The most important period in any fermenation is the first 72 hours or so, that is when most of the esters are produced, so starting fermentation warm doesn't make any sense at all.
Not saying that your beer is going to be ruined but if you don't follow the protocol stated above there is no use fooling around with lager yeasts. You may as well stick to clean fermenting ales.