Hi Rabbi, I have presentation to do tomorow the day before Lag Baomer and its in front of an audience. Am I able to trim my my beard that day?

Shalom, Thank you for your question. In general it is forbidden to trim one’s beard before Lag Be’Omer. However, there are certain lenient opinions. There is an opinion that says the custom not to shave or get haircuts was not accepted by all communities (Radbaz, vol. 2, 687). Some permit shaving and trimming if ones work requires one to look presentable, especially when working with non-Jews (see Igrot Moshe O.H. vol. 4, 102). The Chatam Sofer (vol. 2 Y.D. 348) writes that there was never a custom to refrain from shaving, only from hair-cuts. Even though his opinion is not widely followed, one can certainly rely on it together with other opinions. There are also those who allow shaving in honor of the Shabbat (Shaarim Metzuyamin BeHalacha, 122, 5). Based on this, if the need arises, and one may certainly trim or shave in honor of Shabbat, or even every day if one’s work requires it. It is difficult for me to know the level of need you have – but if you feel that it is unacceptable to appear without trimming your beard, you have room to be lenient. Blessings.