You could start with Rishikesh. From Delhi till Rishikesh then move toward Chopta then Joshimath then Kausauni then Binsar finally stop at jim Corbett and return back to Delhi. Delhi to Rishikesh is 300km Rishikesh to Chopta is 160km
Chopta to Joshimath is 135km
Joshimath to Kausauni is 189km Kausauni to Binsar is 63km and Binsar to jim Corbett is 148km.