You can visit Thimphu and Paro without any extension of permit. For other places you need to get permissions – Haa Valley and Punakha where you can spend 2 days each. You can spend 1 day in Thimphu and 2 in Paro. You may consider this plan: 1. Bagdogra to Phuentsholling – Complete the immigration 2. Phuentsholling to Thimphu – Get the permits for other destinations like Punakha & Ha Valley 3. Thimphu to Punakha 4. Punakha to Haa 5. Haa to Paro 6. Paro to Phuentsholling