The optimal time for option trading, both buying and selling, is during periods of high market liquidity and volatility. Typically, the first hour after the market opens and the last hour before it closes are considered favorable times.
Typically, it's best to wait until your stock has risen to your profit point and then you sell covered calls against it until it gets called away.
But it usually boils down to a few options: Exercise and sell right away for a guaranteed profit but probably higher taxes. Hold on to them for at least a year for a potentially bigger profit (or loss) and lower taxes. Exercise and sell within a year (which usually results in the most expensive taxes)
So, how long should you hold an option trade? Well, it depends on your strategy and your risk tolerance. But if you're looking for a more conservative approach, you might want to consider holding your options for at least 100 days for long positions and 50 days for short positions.
Here is a simple rule: don't ever exercise an option unless you need to in order to exit the position. It's almost always better to sell it. And if you want shares just buy them after you sell the option.