Here's the FAQ
How do I address habitual wakings? (wake-to-sleep and other methods)Have a look at naps option 1 please. This method of W2S is the best start for your LO, the post also covers holding through the jolts.
As I said above you will need to go in and begin your shush/pat at 20 mins into the nap (not 30 as the FAQ says, 30 is too late for your LO), continue to shush/pat right through the transition, and an additional 10-20 mins until she reaches deep sleep (it is usually 20 but with a shorter sleep cycle it may be only 10). The method involves beginning before LO is awake however you can adapt this if you find it more useful to hover by her with a hand ready to begin but then to not begin until she starts to stir then that is fine, all methods are adapted to what works best for your LO.
You can use W2S several times in one nap (I did this with mine when he dropped to one nap, I had to go in every 20 min to W2S but I only had to stay 2 mins, I had it down to a fine art through that tricky phase!) but this can mean staying a very long time in the dark room. Some parents are fine with this, perhaps just one nap per day and have enough energy to keep at it through the nap. Some are not fine, it can be quite depressing sitting in a dark room and getting no Y time or even a cup of tea so if you want to do it just once in the nap that's fine too, if it worked you'd still increase the nap from 30 mins to more like 60 which is still a step in the right direction in sleep training