My suggestions:
0) Do 10-20mins (or more) of very light and relaxing yoga or stretching before the sit
Sit (preferably morning and evening for at least 20 minutes, but for as long as you find useful):
1) If you consider yourself a dharma practitioner, take refuge again in Triple Gem
2) Spend 5-10 minutes doing very slow and relaxed deep breathing, from the diaphragm, going as slow as possible, to help put the body and mind at ease. Start by emptying the diaphragm, then the chest, then pausing, then filling the diaphragm, then the chest, then emptying the chest, then emptying the diaphragm, and repeat the cycle in a relaxed and easy way that feels good. Very useful for the anxiety component of dark night.
2.1) If you feel so inclined, do some deep and slow chanting for 5-20 minutes; good seed syllables are Om, Ah, Hum (for example doing 6 long chants of either one of these) or the mantra "Om Ah Hum" or "Om Mani Padme Hum" in a repeated way, or sing along to a pre-recorded mantra.
3) Bring to mind any teachers or benefactors who have assisted you directly or indirectly in your life and/or spiritual practice, and make a heartfelt thank-you to them. Could also be mentors, employers, family, authors, friends, etc.
4) Take the 5 precepts again, and do your best to live by them for the rest of the day, particularly the vow to not harm yourself or others.
5) If any regret at harm you have caused to yourself or others arises, allow yourself to see it and make a strong resolve to not allow that harm to happen again. Get clear on the distinction between guilt and regret from dharma perspective (guilt is useless anger towards self, regret is useful resolve to change behaviour due to seeing harmful consequences).
5) Practice metta, sympathetic joy or compassion for the remainder of the session. Particularly in relation to the upcoming event and the people involved, if necessary.
6) Close by dedicating the merit in a heartfelt way.
Daily practices I find useful after sit:
• Find wholesome intelligent ways to gladden the mind during daily life, eg being in Nature, with supportive/kind animals or people, etc.
• Read some passages from an insightful dharma text about altruism/compassion, for example written-works by the 14th Dalai Lama, or similar lectures on Youtube.
• Practicing a text such as the Eight Verses of Thought Transformation or Metta Sutta can help a lot.
• Revise the 6 Paramis and check them against your current life.
7) Approach performance situation with attitude of compassion and wish to benefit others.
