leftbrooklyn: On may not shave on Rosh Chodesh even during Sefirah, unless one’s way of counting Sefirah does not include Rosh Chodesh. But if you hold that it’s part of Sefirah, it doesn’t allow you to shave.
leftbrooklyn: When the first day of Rosh Chodesh Iyar falls on Friday, even those who hold the first half of sefirah take a haircut and shave.Since that Shabbos is both Shabbos and Rosh Chodesh, one may take a haircut and shave due to “Tosefes Simcha”. Please see Mishna Berurah Sif Taf Tzadi Gimmel Sif Koton Hay. This reasoning does not apply for this Erev Shabbos.
Abba_S: Sephardim usually hold only the week that Tisha B’av is actually falls in (SHAVUA SHECHAL BO). Does Tisha B’av that coincides with Shabbos (as this year) negate SHAVUA SHECHAL BO or only when Tisha B’av itself is on Sunday (when Shabbos is CHES AV)?
I asked this shaaloh to a Rov here in Manchester. The answer is, even this year, shvua shechal bo is only the day of the fast (10 Av) because it depends on the day we fast, not on the calendar date.