Where I live there is only one Minyan that takes Shabbos in early every week…
I live out of town and there is only one Ashkenaz Minyan that takes Shabbos in early at 7PM every week. At times, both Mincha and Maariv are after Plag HaMincha and before Shekia/Tzeis, which I understand is Tarti Desasri. Should I Daven Mincha Beyichidus before Plag and then join the Shul to listen to Chazoras Hashatz of Mincha and Daven Maariv with the Minyan, or Daven Mincha and Maariv Betzibur regardless?
You should daven Minchah with the Minyan and wait until after Tzeis to daven Maariv. However Kabolas Shabbos can be said with the Minyan.
See sources quoted here:
1. What would be preferred, to Daven Maariv early with a Minyan (in a case where one Davened Mincha after Plag), or to Daven Beychidus after Tzeis? 2. In general from what time can one start Davening Maariv Lechatchila?
Will this delay the Seudas Shabbos? My wife and children would prefer to have an earlier meal. Tzais is around 9:25 this time of year. I understand it is Halachikly okay to start the meal early and be Mekabel Shabbos by Kiddush even before Maariv. Is this recommended?