I'm using a couple of marketplaces to list my domain names. Some of them are Sedo, DAN.com, Afternic, GoDaddy, Uniregistry...
The good point is when you list your domain name on those marketplaces, your domain will be listed on dofo.com (https://dofo.com), too. So if someone searches your domain name on dofo.com, he/she will know that it's for sale.
The time it takes to sell depends on the quality of your domain names and your price expectation. I'd say you have a medium portfolio, and you should expect to sell 2-3% of your portfolio each year, but as I said, it totally depends on the quality.
It seems like some companies and individuals started to register their names with .dev TLD. There are 573 registered .dev domain names now.
You can see all of them on dofo.com: https://dofo.com/search/?extension=dev
The good point is when you list your domain name on those marketplaces, your domain will be listed on dofo.com (https://dofo.com), too. So if someone searches your domain name on dofo.com, he/she will know that it's for sale.
The time it takes to sell depends on the quality of your domain names and your price expectation. I'd say you have a medium portfolio, and you should expect to sell 2-3% of your portfolio each year, but as I said, it totally depends on the quality.