Absolutely now is the time to start! Do you use a clicker? I'd definitely recommend them.
Teach the "watch" command now, it'll be absolutely key to getting focus from these scatterbrained spaniels! It's simply eye contact, held for 10 seconds. Take a treat and move it slowly up toward your nose. As you make eye contact with pup say "watch" and treat. Obviously start with rewarding any eye contact and build duration up to more time. They pick it up so quickly.
Eye contact and watch then becomes the basis for other focused skills close to you including loose lead walking.
So for walking you need to work out which side you want dog to walk. Tradition is left side to leave right for your gun. So if dog to left your lead handle is in right hand and pick up slack with left leaving a J shaped slack.
Lure puppy with yummies into heel position on your chosen side. Say watch and pups eyes should head up to yours, quick treat and walk forward. Say "with me" or heel or whatever you use and if you get just a moment of walking with eyes on yours then reward it. Just keep repeating this. As soon as they stop, repeat the lure back to the right spot and go again. Once they master heel as a position it's easier!!!
You're trying to get focus on your face and body language so that 'watch' command is vital to getting the connection with the dog.
Spaniels are SO biddable and quick to learn you will can get those basic positions and skills fast so sit, down, watch, heel (by side) and then delivery position in front of you (I say front) and middle between legs. They just LOVE learning so it's mega fun. Loads of 5 minutes bursts worked best for us, rather than longer sessions.