The Laws of the Three Weeks vol.3, no. 19
The three weeks between the Fast of the Seventeenth of Tamuz and Tisha B’av are observed with various customs of mourning.
Weddings During this period weddings should not be held . Engagement celebrations may take place. However, after Rosh Chodesh Av one should not serve a festive meal, rather light refreshments if necessary.
Music One should not listen to music during the three weeks. One should not practice music after Rosh Chodesh Av. A professional musician may perform in a gentile’s establishment until Rosh Chodesh Av.
Shehechianu One should try to avoid situations which obligate the reciting of a shehechianu blessing. Therefore one should not eat new fruits or buy new clothing during the three weeks. However a shechianu is recited on a mitzvah like pidyon haben (redemption of the first born son).
Haircuts The custom is to refrain from taking haircuts or shaving during this period. A person who needs to shave for business purposes should at least refrain after Rosh Chodesh Av, or at least during the week of Tisha B’av. Cutting nails is only prohibited during the week in which Tisha B’av falls. In honor of a bris milah which takes place before the week in which Tisha B’av falls, the father, the mohel and the sandek may cut their hair and shave. According to some authorities a married woman or a woman of marriageable age may shave her legs even during the Nine Days.
