When do I take profits? Need some Recommendations on strategy.

Hi all,

I've got a small stock portfolio and I've got a few investments that I would love some opinions on. If any of these offer dividends (D) , I have them set to automatically buy more shares of said stock instead of putting it into my account as cash.

NVDA 27 Shares 123% Gain (D)
XLG 26 Shares 66% Gain (D)
AMZN 5 Shares 65% Gain
USMC 22 Shares 56% Gain (D)
LMT 3 Shares 21% Gain (D)
ADC 11 Shares 18% Gain (D)
VZ 28 Shares 15% Gain (D)
MFA 137 Shares -6.08% Gain (D)

My main question is at what point, if any, should I take my profits (especially regarding NVDA)? Since they all pay dividends, should I just sit on that and let them keep doing so?

Alternatively, at what point do I cut losses and sell off underperforming stock?

Any advice would be great!