Q.
If one says slichos at 10pm for no good reason, are they yotzee?
A.
See question 1833 above, and the Poskim quoted that prohibit, based
on the Zohar and Cabbala, to recite selichos before midnight.
However, we quoted other opinions that permit in need. Some add that
at least one should recite selichos during the middle ashmora or the
second third of the night, which begins approximately two hours
before midnight.
Mishmeres
Sholom and Igros Moshe (ibid.) recommend to recite when in need, at
the time the mishmaros or thirds change. (From the first to the
second).
Horav
Shlomo Miller's Shlit'a opinion, as mentioned above is that in need
and difficulty of staying late at night, one should better recite in
the morning before davening as one does in the rest of the days.
After
the fact, if one did recite earlier the Rov follows the opinions that
one complies.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit'a