Since this will slow down the yeast action, you should leave it at room temperature for 24 hours after thawing. There are a few variables that you learn to understand as you work with sourdough. Even so, the rising is slow and somewhat unpredictable, so it doesn't hurt to add a bit of dry yeast to the sponge. The more sour your starter, the more soda you must add. Begin by using the suggested amount, which is based on average sourness.
Most sourdough recipes call for at least two stages.
The effect is that the mixture is soured and leavened. Then more flour and other additives are mixed in and the resulting dough is allowed to rise once or twice before baking. Thus one must plan ahead in sourdough baking one or two days. I have tried some recipes that take four days, but I didn't think them worth the trouble. A purist would use no yeast in a sourdough recipe, but I am no purist.