When my daughter and I started vaping, around 3 years ago, we had no idea about steeping. Luckily for us, we were using a vendor whose eliquids tasted good to us right out of the mailbox using the equipment we had. We would place a monthly order, trying to estimate how much each of us needed to last until the next order. Some of the eliquid naturally steeped by the end of the month.
Then I discovered ECF, and found out about steeping. Due to a strict budget, we still ordered eliquids the same way - try to estimate how much would last us both for a month, and vape what we wanted when we wanted. We started trying new vendors, and continued as above.
We have no "hard and fast" rule for steeping for our vaping pleasure. When we are trying a new flavor from a trusted vendor, or trying a new (to us) vendor, we will usually try the flavors right out of the mailbox. If we like the flavor "as is", we continue vaping. If we think it still needs something, we let it steep. Our extremely complicated steeping method is to put flavors we want to steep, or that we are not ready to vape immediately, into the el cheapo toolbox I got from Walmart special for vaping supplies, leaving the caps on (we have dogs and cats). I mark the date I receive a shipping notification from the vendor on any eliquid bottles that do not have a "born on" date, so that I have some idea how long I have had the eliquid sitting around.