There's seldom a right time to be let go. If you uncover extreme personal hardship, take that into consideration. Use preventive law. Pre-plan the termination meeting. Provide the best outplacement counseling program you can afford, especially in difficult cases.
Some programs are so short they're outplacement in name only.
Don't wait for days, weeks, or even months to begin outplacement. The first few hours after a termination are critical. Candidates don't know what outplacement is. They're often confused, shocked, and embarrassed. They don't know what is in their best interest.