We are travelling in Vietnam for approx 3 weeks in April and will likely be flying (hanoi-ho chi minh) and return to (Phu Quoc from Ho chi Minh) to save time
How far in advance should these be booked? I would like to leave it as flexible as possible however I expect I may have to book a bit in advance as prices may be high if only booking a few days before flying.
Any tips would be appreciated (on booking or on airlines)
Around 30 April and May Day it will be our national holiday, so flights may be fully booked. Other than that time, I don't think you will have any problem with booking your flights. The highest price for one way flight HN - HCM is US$100. Alternative airlines is Jet Star Pacific but their services are not so good like Vietnam Airlines.