I know you guys are probably getting sick of me singing the praises of clicker training <g> but here I go again 
I can only relate though what I've done with Chi and how it has worked for us. If I'm not mistaken Apollo is about the same age as Chi, (bout 5 months) right?
Her heel is a work in progress but walking on a loose lead is down to almost a fine science. Since we don't have a fenced yard and very few safe places to allow her off lead, the vast majority of her excersize is on the end of the leash. Because of that, I don't like to keep her at a heel unless I have to have her under complete control and her utmost attention. For the most part she is free to sniff and walk ahead of me as long as the leash is kept loose. How did I do this, you may ask? With the clicker and lots and lots of dried liver. As soon as we started our walk, before she had the opportunity to pull I would click and treat (that really gets her attention) and then would click and treat sporatically throughout the walk. When she pulled I stopped dead and did not move, as soon as the leash was loose and we were able to get at least a few steps she got another c/t. In a matter of just a few walks she realized that she only got the yummy when the leash was loose. I have found though that about half way through our walks she, like Apollo
gets a bit full of herself and wants to act out. It was hard initially for me not to pull her back or give her a correction. But now when she does that and gets silly I put her in heel until she calms down a bit and then we try again with the "let's go" walk. I also tend to really slow my pace while she's in heel if she's excited. She's young and we're both still learning so I really try to set her up for success. It seems to be working wonderfully for us. I use only a flat collar but am thinking about switching her over to a harness soon.
Good luck and keep us posted
How are his ears doing? Would love to see pics 
I can only relate though what I've done with Chi and how it has worked for us. If I'm not mistaken Apollo is about the same age as Chi, (bout 5 months) right?
Her heel is a work in progress but walking on a loose lead is down to almost a fine science. Since we don't have a fenced yard and very few safe places to allow her off lead, the vast majority of her excersize is on the end of the leash. Because of that, I don't like to keep her at a heel unless I have to have her under complete control and her utmost attention. For the most part she is free to sniff and walk ahead of me as long as the leash is kept loose. How did I do this, you may ask? With the clicker and lots and lots of dried liver. As soon as we started our walk, before she had the opportunity to pull I would click and treat (that really gets her attention) and then would click and treat sporatically throughout the walk. When she pulled I stopped dead and did not move, as soon as the leash was loose and we were able to get at least a few steps she got another c/t. In a matter of just a few walks she realized that she only got the yummy when the leash was loose. I have found though that about half way through our walks she, like Apollo
Good luck and keep us posted