Hi and welcome! Sorry about the loss of your first lab, that is a hurt that only pet lovers really understand. How long to wait is very individual, some find a new furry love within a few days, others wait a few years. It's really what works for you, we cannot tell you your truth.
Since you are married, I'd want to have my husband on board with getting a new dog. Fences can be an issue with some rescues, you would not be alone in missing out on a pup that might otherwise be a great match for you. I did, but the sweet girl I found after that is just so delightful, I feel like it worked out the way it was supposed to for her and us.
As for Craigslist, I have not but I think one of my neighbors got a lovely yellow female lab through a Craigslist post and she has been a wonderful dog, once she stopped escaping their yard. If the Craigslist thing moves forward, maybe the current owner would be willing to meet you at a local park or somewhere not at their home, if getting stabbed is really a concern to you. And I wouldn't go alone no matter where you meet up. If your husband comes with you and gets to meet the dog and you both feel it's the right thing for you, it will go a long way to easing the new pup into your lives.
Good luck, let us know how things work out!