^^^ Yep
I usually cast 5 - 10 times and just dump them into the scrap pile to get the mold up to temperature. Sometimes it takes longer.
I'll fill the mold and leave a puddle on top of the sprue plate. When the mold is at temperature, it usually takes a few seconds for the sprue puddle to solidify.
You then need to keep casting at a regular rhythm to keep the mold hot and at the right temperature. If the sprue cools too fast, cast faster. If the sprue is taking a long time to solidify, cast slower.
Each mold will be a little different. Over the weekend, I used 5 different molds and cast a bunch of bullets. When I switched molds, it took me a few minutes to learn the mold and get a rhythm going.