Domestic Vietnam Flights - when to book ?
 

I'm just under 2 months away from flying Vietnam domestically (Ho Chi Minh - Phu Qouc, Phu Quoc - Hai Phong, Hanoi - Danang, Danang - Ho Chi Minh) - I've been tracking flight prices and they really haven't changed, when is the sweet spot to book ?

If these are the same airline that I've been watching, the flight prices look pretty low to begin with. I'd love to see if they would drop a bit more.

That's a lot of flights. Vietnam Airlines?

Vietnam airlines for most part, but only Vietjet flies Phu Qouc - Hai Phong

May try JetStar for HCM to Phu Qouc, I read that Vietjet is a disaster out of HCM - which I'm going to assume the same out of Hanoi

Personally, I would just book it now. I assume you're holding out to see if the prices go down? How much do you think you could really save? I can't see saving any more than tens of dollars.

tens of dollars x 3 pax x 4 flights = many dollars

Personally, I never win at the price waiting game. For my trips, it seems like the price usually go up as I get closer to the departure date.
I just pay the price if it is reasonable to me.
I checked a mid-week in June for one-way for SGN-PQC, HAN-DAD, DAD-SGN on Vietnam Airlines website. The coach ticket prices I saw for each of these segments range from 58 USD to 72 USD. The trip duration is between 1 hour to 1.5 hour. For me, in these cases, the price is certainly reasonable and I will buy them now.
I always stick with Vietnam Airlines by the way. I do not have any experiences with the other local airlines but I prefer to stay with VNA.

Writing this from Hue, overlooking Perfume River.

If it is just two month left, than prices unlike to go down and most likely will go up, based on my experiences with intra-Vietnam flights.

For cheap flighs with VN one should book flights at least 6 month before departure if you want to catch their Eco fares. The same applies for VietJet. You can sign up for their fare newsletter to know when is time to book.

Alternatively/in addition you can setup fare search at Skyscanner with target prices but, unlikely you get great deal right now two month before departure.

Three words of advice:

1. If you have connecting flights with separate tickets make sure you have at least 4h between flights. Not a single time my intra-Vietnam flights departed on the time shown when I booked them. Even with VN within 2 month of departure time flight moved three times forward and back. At least VN notifies you via email, Jetstar and VietJet - do not, unless you sign up for paid notification service (not a joke).

2. Avoid booking the very first and last flights - they are cancelled most often.

3. Check traffic conditions on the date/time of the departure - in Saigon it might take 45min to travel 5km via car.

You should book at least 3 months in advance to get the reasonable price tickets.
Jetstar Pacific and Vietjet Air are low-cost airlines, much cheaper than Vietnam Airlines.

Did this change within the last year?

I took several flights to/within Vietnam last summer on VietJet. Yes, the flight times were constantly changing, and with each change, I was notified by email. But I never paid for any special notification service.

Very latest example it with Jetstar which wants additional fee for sending SMS notifications. I remember seeing something similar with VietJet for international flights but can't be sure.

I have booked several flights last minute in Vietnam over summer and prices didn't seem to go up by much. If your itinerary is not set I would wait.

I'm just guessing, but I would imagine that they do not have dummy flights. They just didn't sell enough seats to make that flight profitable, so they cancel it and move everybody to the next day. That way the plane has more passengers and they can turn a profit.

Imagine if you worked for that airline as a flight attendant or pilot. You would never know when you're supposed to go into work!