Small containers make intensive culture much easier. This time of year heat isn't an issue, and if you put 30 or 40 newborn fry into a 1 qt container it's easy to overfeed heavily and then change enough water enough times a day so that the overfeeding and lack of filtration aren't problems. That's the trick to rapidly raising fry and there really is no shortcut. Fwiw I just did a water change on a tank containing two pair of Blue Gularis Killies that were born on 4/28/12, and raised in the manner I describe until they were about 1.5", which was about a month. The fish are now 3.5" and the change triggered both pairs to spawn for the first time. The fish max out around 5" which should be by Xmas. Most small fish, such as Tetras, Rasboras, and Livebearers we keep should reach their full adult size in their first year.