Vietnam travel itinerary. Need suggestions

Hi all, I am doing my first Vietnam trip and need some suggestions. Trip dates are 25 Nov - 4 Dec, but excluding travelling to and from Vietnam, it will be 8 days in total. Here is my current plan:

25 Nov - Reach Ho Chi Minh City by 8PM

26 Nov - War Remnants Museum, Ben Thanh Market and Independence Palace

27 Nov - Notre Dame Cathedral of Saigon and Mekong River Delta

28 Nov - Fly to Da Nang and then cab to Hoi An. Explore Hoi An

29 Nov - An Bang Beach and Precious Heritage Art Gallery Museum

30 Nov - Fly to Hanoi, visit Hoàn Kiếm Lake and Old Quarter

1 Dec - Hạ Long Bay

2 Dec - Temple Of Literature and Ho Chi Minh's Mausoleum

3 Dec - Not decided. I can extend my stay by 1 day in any city

4 Dec - Travel back from Hanoi

Should I add something or remove something? My budget is around 500-700$ which includes stays

Thank you