15 days itinerary

Hi everyone! I’m planning a 15-day Peru trip end of Sept and would love feedback on whether this itinerary looks reasonable:

Day 1–2: Lima
Day 3: Fly to Cusco, taxi straight to Ollantaytambo
Day 4–5: Ollantaytambo / Sacred Valley
Day 6: Aguas Calientes
Day 7: Machu Picchu, then stay in Cusco
Day 8: Cusco
Day 9: Overnight bus to Arequipa
Day 10–11: Arequipa (not doing Colca Canyon)
Day 12: Overnight bus to Nazca
Day 13: Nazca Lines, then stay in Paracas
Day 14: Paracas
Day 15: Back to Lima for fly home

Also, for the Cruz del Sur overnight buses, when is the best time to book to get the best lower-deck seats? Thank you!

I'm a female solo traveler, is it safe to wear a belt bag in the front for cards and cash? I've read people can easily cut the strap and snatch it. Thank you!