You can make a witch bottle at any time - the best time is the time that works for you. However, if you want to work with correspondences such as moon phases and days of the week, there are a few different ones to consider.
The Waxing Moon is a great time to do spells of growth. The moon is growing larger in the sky and so is the energy associated with the moon.
The First Quarter Moon is a great time for luck spells and growth. The moon is in the First Quarter today!
The Full Moon is a great time to do any type of spell! The next Full Moon is next Saturday, February 24th.
You can learn more about the moon phases here → Moon Magic: Spells for Every Lunar Phase – Spells8
Thursdays are great days for spells involving business and money. Fridays are great for love and beauty. If the day has passed, you can work with the hour of the day, instead. So today, in my area, the best time to do work related to growth, business, and money is between 4:15 PM and 5:08 PM when the day is ruled by Jupiter.