Hiya Candy and welcome
a lot of gents love the naughty forties and your age and maturity can well be to your advantage
imo there is no right age to do this as men in general want differebt things ,some may want the pretty young woman but for others thats not an option they prefer the older ladies
there are plenty of places to advertise www.prettybigescorts.com ,this site caters for the bbw escort and is only ?20 per year to advertise ,its no2 on my website stats and i wouldnt be without it
there are also a lot of sites you can advertise on if you need any details then please let me know and i will be glad to help
use your maturity and your size to your advantage
good luck
xxxx

Goodness yes! You haven't heard of Grandma Libby, have you? She was in her sixties and did quite well as far as I know.
There are quite a few mature escorts out there, some in their forties, some in the fifties and beyond. There is a market for it. It is a niche one but it's there. Judy's Mature Escorts is an agency that have been going for few years http://www.judys4.co.uk/home.php .
If that's how you'd like to advertise yourself, go for it. Google the words "mature" and "escorts" to see how the independents do it.
Good luck.

I used to know someone in her early forties & she was very popular because of her personality and her sexy looks but I also heard so much slaggin off by men who preferred "young & pretty" calling her "ghastly". 

she was later snapped up by someone who fell in love with her and then she retired.  there are nice men and ugly punters in this industry but never get beaten by idiots