Q. A person came to shul on Friday afternoon to daven Mincha. By accident he started saying the Friday night S"E (Maariv) instead of the weekday Mincha. What should he do - continue with the Friday night S"E and then repeat it as tashlumim for the Mincha that he missed, or switch back to the weekday brachas?
A. Horav Shlomo Miller's Shlit”a opinion is that since the intention was to daven Mincha and it is also the time and occasion for this tefilah, and only by mistake he started Maariv instead, as soon as he becomes aware, he should switch to Mincha. This applies even if he already recited the brocho of Mekadesh Hashabbos.
The Rov insists that the above holds true only if it is still before the shekiah, as one should not daven Mincha after sunset. (However, in practice some traditionally do daven Mincha, at least in need, some limited time after the shekiah).
Rabbi A. Bartfeld as as advised by Horav Shlomo Miller Shlit'a