Hi Lori, if your home is generally at least 68F, you should be fine leaving your starter out at room temperature. I just created a starter from scratch and my home hovers around 68-70F during the day, and cooler at night, and the starter process worked fine. I worry a little about placing your starter in the oven with the light on, as this can generate more heat than you expect, which could be causing issues. I would try leaving your starter out at room temperature during the day, and if your home gets really cold at night, you could try boiling some water on the stove and pouring it in a pyrex cup and placing that in the microwave with your starter right before you go to bed at night. 

If you happened to experience an initial burst of rising on day 1 or 2, followed by an extended lull in rising, this was likely due to a type of bacteria that gives off carbon dioxide rather than true yeast activity. Unfortunately, the presence of this type of bacteria early on tends to result in a subsequent delay in the yeast kicking in. The good news is that patience almost always pays off when it comes to sourdough starters, and even if you continue exactly as you're doing, your starter will eventually begin rising predictably. 

If you think this is what happened with your starter you could also adjust your feeding routine a bit to make the starter environment more acidic, which seems to help encourage the yeast to join the party. For this alternative feeding routine you would want to:

1. Feed only once a day

2. Feed with whole grain flour (whole wheat or whole rye)

3. Feed with a ratio of 2 parts starter : 1 part water : 1 part whole grain flour (by weight). For example, using our original starter recipe, your modified once a day feeding would look like this: 113g starter + 57g water + 57g whole grain flour. 

Once your starter begins rising predictably (twice) it's important to resume twice a day feedings, which will further promote yeast activity. You can also shift back to the 1:1:1 ratio of starter:water:flour (by weight), and gradually, over the course of several feedings, transition back to feeding with unbleached all-purpose flour. Once your starter is rising predictably with the 1:1:1 ratio and AP flour then your starter is ready to start baking bread! 

Another option, whichever route you decide to take, is to reduce the size of your starter, at least until your starter begins rising predictably. Our smaller starter recipe involves maitaining only 60g of starter (in an 8-ounce canning jar). If you want to try our regular feeding routine that would be: 20g starter + 20g water + 20g AP flour. For the modified routine I mentioned above, your once a day feeding with a smaller starter would look like: 30g starter + 15g water + 15g whole grain flour. 

One more thing: in order to see the type of "doubling" behavior we reference, it helps if you have your starter stored in a clear straight-sided container that is taller than it is wide. For our regular starter recipe, a wide-mouth quart-sized canning jar works well. It's harder to see the starter rising if you have it stored in a wide bowl or Tupperware container. 

I hope this helps! Let us know how it goes! 

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