Early Shabbos

Hello.
May one begin l’chu naranana on Erev Shabbos before plag hamincha?

If “yes” is this b’deavad or l’chatchila?

If “yes,” until what point in the prayers may one pray before plag hamincha?

Thank You

You may not begin prior to plag hamincha.

All the best
Rabbi Shay Tahan