The best time to train your dog or mine 🙂 is when he/she is hungry and when they have been alone for a time, for example if you have been out for a time, preferably 2 hours or more.
Titbit training is by far the easiest method of training any dog, it only goes wrong when the food is withdrawn to early in the learning process or when the dog controls when he/she gets the titbit, to be sure they do not made sure you are giving the food rather than the dog taking the titbit. For maximum results the dog must want the food, if they have just been fed they will not be so keen, even if the titbit is something exotic like chicken or sausage!
By far the most important factor, one that is often overlooked by pet owners is to train the dog when it is not saturated with your company, for me this means that I will shut my dog in my utility room to artificially create his want to be with me, this makes him 50% keener to please me when I start training him. Whereas the dog that has just been having a cuddle on your lap will have much less motivation to work for you, why should he/she?