Hello and welcome to Trip Advisor.
I think you have the itinerary in sequence.
15th visit Nageshwar and Beyt Dwarka (2 night)
16th visit Harsiddhi mata, Porbandar and Somnath
17th & 18th visit Diu
19th visit Sasan Gir (book your permit online www.girlion.in)
20th return to Rajkot.
Have a good trip.
14th oct - Jamnagar to dwarka 240 km (4 hrs)
15th oct - beyt dwarka , nageshvar
16th oct - leave for somnath (dwarka to porbandar-105 km, porbandar to somnath-135km)porabandar and harshad (temple of harsiddhi mata) u can visit between dwarka to somnath .
17th oct - leave for diu (17&18. 2 night diu)
19th oct - leave for gir (1 night gir)
20th oct - leave for rajkot.