Hi Sabs
Perhaps I can share my experience. My 10 week old is also a tummy sleeper and almost always wakes at the 30 min mark. She also turns her head side to side when she wakes and squirms a little and then eventually cry out. Sometimes she would only cry out at the 40/45 min mark or even 1 hr. I think it's the jolts that wake her and she's not able to make the transition back to sleep.
I've tried httj but it worked only once and I suspect she could have slept past the 30 min mark on her own anyway.
w2s doesnt work for us. She wakes up and I have to pat her back to sleep.
I extend her naps by patting her back once I see that she needs help. I shield her eyes with one hand and pat her back with the other..light pats at first and then firmer pats if she cries louder. If she's OT, she would work up a frenzy, I would then try shh..hhh and pat faster to get her to focus, she would usually settle after a while. Once she's calm, I slow down my pats and soften my sh..hhh..and then pat slower and slower and lighter and lighter before I stop, then I leave my hand on her back for a bit while still shielding her eyes.
She goes back to sleep on her own by slowly turning her head side to side again. I only intervene with light pats if I see she's getting frustrated (ie. turning her head constantly or rubbing her face on the mattress). Once I see she's calm and can go back to sleep on her own, I take my hand off and leave the room. The whole process normally takes 15 to 20 mins.
If she's super OT (usually because my mom who is helping me did not manage to extend the previous nap), she screams and screams through the patting, I would hv to carry and pat her till she's drowsy and then put her down again and repeat the process above.
I am hoping I can intervene less as she gets older but this is only way I can extend her naps.