Only you can decide if you're comfortable enough with yourself to try to initiate a new relationship. All of us deal with this differently. If you feel like you need to focus on yourself to get 'er done, then that's what you need to do. If you feel like having a significant other would be a helpful resource of support, then obviously don't close any doors on possible relationships
I have two slightly conflicting thoughts on the subject.
First one is: Ideally, I do not believe weight loss/maintenance should interfere with life. You shouldn't put something off until you lose X amount of pounds. Hopefully, you can enjoy all of life's experiences before, during, and after the weight loss process. It's like how people often put off dieting until after the holidays or something. Weight loss and then maintenance should continue to happen no matter what. Part of the journey is to learn how to navigate these obstacles (dating, holidays, trips, etc) with our new healthier lifestyles.
Second thought, which contradicts my first, is that dating might create an unnecessary challenge in the weight loss process. Especially when you're first starting a new lifestyle and forming new habits, it takes a lot of concentration and will power to stay on track. When you're all caught up in the new-romance twitterpation, weight loss might take a backseat. What if he gives you chocolates? Wants to take you out to dinner every weekend? Get ice cream and go for a romantic walk?
Again, going with my first point, hopefully we all learn to deal with these challenges and are still able to enjoy everything to its fullest, but it may make the initial habit-forming phase harder.