Question:
Can you pray mincha in a place that has already received Shabath in advance?
Answer:
A person that is in a shul that was mekabel shabbos early, even if he was not mekabel shabbos together with them, he should still not daven mincha inside of the shul, rather he should daven mincha outside of the shul. The reason for is since the congregation of this shul made it shabbos already, he shouldn’t make it look like it is still a weekday, therefore he should not daven mincha inside the shul.
Best wishes
Sources:
O:CH 263-15, M:B 263-59.
