What age do you suggest electric collars for training?

I would never use a remote collar for this type of issue with a puppy that is so young. We use management tools like leashes, ex-pens, and crates to keep our puppies from practicing the wrong behaviors while we build a training relationship with them. I've raised countless puppies and they are on the leash at all times, even in the house, unless they are in their crate or ex-pen. We set them up for success using management and then train them what we expect in a way that is fun for both of us (using food & marker training. I see you already have the food video. You can start that work now).

There is no set age for using the e-collar, but I will say that I want my dog to have a clear understanding of a number of core skills and behaviors before I introduce the electric collar. This timing (like most things in dog training) is dependent on the dog and your skill set as a trainer. I would say on average most dogs are at LEAST 12 months old and have all the basics on leash in place before we introduce the remote collar.