how much time would be required for a competent mechanic to replace a oil pan

Do it yourself,,you can save so much money,,its only a pan and a bunch of small nut and screws,,use a mercedes gasket sealer ,,,stickt the new pan gasket up there,,where it will stick there,,put up the pan,,insert scres,,then with a ratchet tighten them up and your done,,youtube,,or fcpeuro for videos