It's different for everyone. You should get to a place where you are happy with yourself, and the general direction of this new life.... and then you'd be ready, IMO.
I met someone 10 mos. after being separated. Divorce didn't actually happen for about 3 years....nobody pursued it, etc... Some people don't understand dating while separated, some people get it.
For me, there is no "separated".... either you are married or you aren't, and "separated" is the time period of waiting for divorce paperwork.
Look into single parent activities. There used to be "Parents Without Partners"...not sure if there is anymore. There is also meetup.com which is separated by activities... dancing, bowling, hiking, dinners, dog walking, everything. They are nationwide and might be near you. They are also group activities, some people there are looking for love, some are just looking for companionship...but you just sign up for things you enjoy doing anyway!