We were told by our breeder to let off lead asap, when they are young and scared to leave you! I only do this when I am 'off road', so to speak, in a field or track etc, so it might be different to you are we are very rural. Also, I have worked really hard on recall, he will do anything for liver and comes back when called without fail (so far!!!). He doesn't go far anyway but loves the freedom, today in the snow was magical!
I see nothing wrong with giving him a chew and letting him be under the table, with occasional treats or praise for being calm and good.
Many thanks for the heel and lead information, I have a slip lead and a normal lead, our friends have always used a slip lead for their working gundogs, with a combination of consistent/intensive training? I see no issue either but am no means the expert!! I think this will be my main focus in the next few weeks, everything else he 'gets' pretty easily but not the lead work. Realistically, we are rural and will only use the lead to get somewhere 5 minutes away like a field or track but I want him to walk nicely anyway.
I also have the same whistle but keep forgetting to use it, with a combination of treats, poo bags, clicker, lead etc etc.
Interesting information re commands too, thank you. We have been doing several commands in a session, which he gets fine but might not be the best way to do stuff? Mmm.