Haircut for a mourner on the eve of a holiday when the holiday cancels the thirty days

A mourner whose thirty days of mourning for his brother are canceled by Sukkot, and there are no barbers willing to cut his hair before Mincha, can he be lenient and get a haircut earlier?

For those who follow the opinion of the Shulchan Aruch, they can be lenient and get a haircut from the morning. For those who follow the opinion of the Rema, in pressing circumstances, they can be lenient and get a haircut from midday.

Sha'ar HaTziyon, Siman 548, Se'if Katan 23. From the words of the author later in Se'if 10, it implies that it is sufficient to do this after midday, and one should not say that the intention of the Rema is because bathing is possible at night, therefore he was stricter, as one who examines Yoreh De'ah, Siman 399, Se'if 3 in the gloss will see that the Rema was also strict regarding laundering and haircuts. In truth, the author disagrees with the Rema on this matter, and in his opinion, in our case, there is no need to wait until evening, and in pressing circumstances, one can rely on leniency according to the author, as the words of the Rema are only the opinion of the Hagahot Ashri in the name of the Ra'avyah (and what is cited in the Rema in the name of the Mordechai is not accurate, as it is not found in this manner, and also in the Hagahot Maimoni, two opinions are brought: some are stringent, and some are lenient in this matter from the morning, see there). From the words of the author, it implies that in our matter he is more lenient, and there is no need to wait until after midday, as also written in Ma'amar Mordechai, and his ruling is that we should be stringent in this as in Se'if 10.