Transfection with Lipofectamine 2000 works extremely well although you need to titrate the amount of Lipofectamine 2000 and the DNA amount before you start. We usually have a transfection rate of 20% without any cytotoxic side effects seen in other cells with Lipofectamine 2000. Dependent on your vector you can start selecting 24-48h after transfection.
Although we keep stable transfectants constantly in selection medium in some cases the expression of the gene of interest will (drastically) decrease over time in our hands.