Some spells are believed to be more effective when the moon is at a certain phase as each phase relates to certain goals you may be trying to reach. I believe I have read suggestions in the past regarding times of day as well but just like moon phases it varies from spell to spell. I would think some spells regarding changes or seeking new beginnings might be better cast in the morning for instance but that's a theory.
An article on this site that may help is https://www.spellsofmagic.com/coven_ritual.html?ritual=795&coven=245 and another interesting article from the internet is https://exemplore.com/wicca-witchcraft/How-to-Cast-Spells-Magical-Timing-with-Moon-Phases
This depends on a few things. When do you feel more comfortable or magical? Do you want to follow traditional planetary correspondence?
If you go off of traditional planetary magick, each of the 7 days has a ruling planet. Each day also has 12 day hours and 12 night hours. Each of those hours is ruled by the planets as well in a cycle. The planets all have different things that they rule over than also correspond to spells. If you want money, you'd do a spell on the day and hour of Jupiter which is Thursday within the hour of sunrise. If you wanted to cast a love spell, Venus rules over relationships and love so her day and hour would be Friday during the hour of sunrise.
I personally take into account the moon phases (Waxing for bringing in, waning for banishing, for example); Days of the week (Friday for love, Wednesday for communication, etc). And what zodiac the moon is in (in Libra = love, Scorpio = revenge, etc) And of course moon void of course. When the moon is VOC I don't do any spells at all because they won't work.
You can find these correspondences online of course but also many apps will tell you the moon phase, the zodiac sign it's in, and when the moon void of course is. Theres also an online calendar on a website called Zodiac Arts
As for time of the day i personally only work at night. That feels best for me but also because that's when I have more energy and usually the free time and privacy. I think that's just personal preference.