We breed in late summer and year end/beginning, so we have puppies ready to go home around Christmas time and Memorial Day (ish). That also allows us to show our dogs in the summer, mow the acreage, mend the fences, enjoy our hobbies, etc. Heat cycles aren't always perfectly regular, so this can change a bit.
One of my favorite things is to pretend to be shopping with a puppy in my cart at Home Depot and "run into" a family with children who want a puppy. The kids get to hold the puppy and, of course, fall in love. Then they learn that it is THEIR PUPPY to take home with them! When the Home Depot staff sees me come in with a tiny puppy in my basket, they all gather around the ends of the aisle where I am to watch the kids be surprised with their puppy! It just doesn't get any better than that!
If you reserve a puppy for one of these time periods, and you don't find the puppy you want or your circumstances change, your deposit can be moved to the next litters.
Fair warning: Our puppies are often reserved before we breed and before they are born.