That's a hard question to ask. I don't do this as full time job but I will say when I have a lot of free time on my hand, I can do a character in 2 to 3 weeks. I'm not sure how that equates to in hours but overtime you are more than likely to recycle some of your body parts for other characters or make minor modifications. So the process will always vary. People like to recycle things like the eye expressions, mouth expressions, eyebrow expressions and hand expressions which usually takes up the bulk of the work. In addition, you can eliminate the need to draw some of those expressions if you plan on using one of reallusions standard body parts as well.
I think one of the most important things you can do is focus on the over all look of the character first and test the layering. Create just one angle, don't worry about all the different eye,hand and mouth expressions. You want to first determine how your character layering should look. For example do they have long sleeves or short sleeves? If so you drawing style will need to be different and your arm, forearm and hand layering will need to be different. Another thing to consider is how complicated is the character. If you are drawing a vector base character, you want to make sure that your line work will import correctly and hopefully your file size is not too large. To much line work and CTA2 will not behave correctly, the characters movements can be come glitchy or the import will be horrible.
Here are some example of two set of characters with simple line work and with a lot of line work.
The last thing you want to do is spend a very long time on a character only to find out that you can make the layering work the way you like or the character does not import correctly.
Make sure you rig the character in one angle, import the character in CTA and focus on body testing first. You want to ensure the character will behave the way you intended it tobehave. The multi expression parts of the face is by far the most time consuming portion of the character. If you are doing a single angle character then you won't have too much of a headache. But if you are doing a multi angle character you are literally creating hundreds of body parts. For example if you are doing the standard 13 eye expressions and they are symmetrical, You will be creating the eye sets for 3 angles (front, 3/4 and side). 13 X 3 = that's 39 eye expressions. However if one of the eyes is unique for example one eye has a scar or a patch or something, now you have to work on 6 angle instead of 3 because you can't just flip those same expression over to do the other angles. Instead of drawing 39 expressions, you are now drawing 78 expressions and that's just the eyes. These same rules apply to almost any body part. If it's not symmetrical you will be increasing your level of effort with the character. Take this information into consideration when you are getting started. If this is your first time creating a character, start off with a simple symmetrical character before gravitating to a challenging one. All characters are not created equal. The last thing you need to consider which could be minor is whether or not your character will be render style compatible. If you have a simple character, it's not that challenging to have it RS compliant. With CTA 1 you could name your color group yourself, which was great, because you could have how many color grouping you wanted. However, with CTA 2, you have to assign your color grouping so you are limited to how many color groups you can assign. RS may not be a big thing for most people, however for me, it's very important. I do most of my characters for the Market Place and a few as freelance work. Most freelance work is more detail and complicated, however they are not as concern with RS. However, the characters I do for the MarketPlace I prefer all of them to be RS to ensure my customers get the most out of their character. Having the ability to change the shirt or whatever body part to the color of your liking is just as important as having my character behave the same as Reallusions pre-made characters. I have purchase other peoples characters in the past and some of the motions don't look the same or they are not RS compliant. This is not a big deal if you are doing your own key frame animation but you need to know who your main audience is for these characters.
Most of the people who buy these characters are not seasoned animators and they rely heavily on being able to press one button a have an instant walk cycle or for the character to have an automatic lip sync. So I ensure that those needs are met when I create my characters. I know that if I can meet those demands, a seasoned animator will be able to way more with my character than a newbie, but at least if I can cover the basics, my character is now ready for all levels of animators.
Anyway hopefully I didn't bore you with all of this information, but after doing a ton of G2 Characters this is the best tips I can suggest. Having a good plan before getting started will be the major factor in sticking with it or giving up on it.