Hi Wanda, with an established starter it will develop a recognizable pattern of rising behavior, although the timing can change, depending on the seasons and how warm it is in your house. Warmer temperatures tend to speed up rising and fermentation, while cooler temperatures slow things down. Starters maintained with wholegrain flours ferment more quickly, and the consistency of the starter (liquid or stiff) can also affect the rate of fermentation. In other words, different starters will all perform a bit differently, and the exact same starter is likely to change seasonally, so it's important to get to know your starter and it's normal behavior, and to recognize and adjust your feeding routine when your starter begins to behave differently.  

With our sourdough starter maintenance routine (100% hydration starter, 1:1:1 ratio of starter:water:AP flour, by weight) it generally takes about 6-8 hours for the starter to peak, but this can vary considerably depending on temperature and activity level. Right after you feed your starter it should be a thick, but easily stirrable paste consistency. As it rises and ferments it will become thinner in texture and develop bubbles throughout, which is what causes the rise. At the peak your starter should be at least double in size (assuming it is stored in a tall jar, rather than a wide bowl or Tupperware container). The surface should look rippled with some large and small bubbles (although this can vary, depending on the size of the starter and the type of container you have it stored in). Usually the starter will hover at the peak for some time, and then gradually the bubbles within the starter begin to deflate and the starter looks a little creased or dented on the surface, with smaller bubbles beginning to gather there. Sometimes it's easier to recognize this "just past the peak" interlude, since it's hard to know whether a starter that is peaking will continue to rise, or if it's about to begin falling. The peak, or just past the peak is a window of time rather than a precise moment, so it's not like you have to time everything to the exact minute. 

If the starter is allowed to fall completely it will ultimately deflate to the level it was right after feeding, and will generally be much thinner in texture, with perhaps some frothy bubbles on the surface. If you always feed your starter when it has fallen significantly this tends to lead to more sluggish yeast behavior. 

If your starter is still in the creation phase it may not have developed a consistent rising pattern, or may not be rising at all yet. At this point, feeding at the peak doesn't really mean much. Generally speaking, you can get by with once a day feedings until the starter begins to rise, and then you need to shift into a more frequent feeding routine to keep the yeast activity high. This is the point where you want to begin to pay attention to rising behavior and adjust your feeding routine to line up closer to the peak of rising. 

Say it's July and you're going through a heat spell and your starter has suddenly started peaking after 3-4 hours. Rather than waiting until the 12 hour mark, or shifting into a feeding routine that requires you to feed your starter 6 times a day, you may want to take some actions that will help slow down fermentation and allow you to continue feeding your starter twice a day, while catching it closer to the peak. To that end you can use cooler water to help slow things down, and also decrease the percentage of starter as compared to water/flour fed. Lowering the percentage of starter in each feeding means you'll be essentially offering your starter a larger meal, which will take it longer to consume and ferment. This might mean shifting to a 1:2:2, or even a 1:3:3 ratio (starter:water:flour, by weight) during the summer months, and then returning to something closer to the 1:1:1 ratio when things cool down in the fall. As a short term solution in the summer months you can also stick your starter in the refrigerator if it has peaked early and you're not able to feed it again at that moment. 

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

Barb

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