how soon is too soon to buy airplane tickets

Stacey, start looking at airfares now. You can use internet search engines (google flights,etc) to get a sense of what the usual price range for your flight is. Keep watching the price and for sales. If you see a price that you know is a good price, go ahead and purchase. There is no “magic” time. The best magic is a well informed consumer who has done his/her homework.

A note of caution. When the time comes to make your actual purchase, use the airline’s website to eliminate needing to go through a third party for any future changes or issues.

Most airline tickets are available starting 11 months in advance of departure. However, it's possible for flight schedules to change by the time you actually travel.

There is no "right time", there is no magic formula that can tell you when to pull the trigger on airline tickets.

Most airlines won't have flights available to book more than around 11 months ahead (they're just not loaded in their system - some a little more than 11 months, some a little less, and some a lot less - some low cost airlines only load their schedules a few months in advance and the cheapest seats can get snapped up quickly, so you need to pay attention).

Six months is not too early (not at all). Your best plan would be to start watching things now, continue watching, be patient and invest some of your time, to get a good sense of what prices are like - you will see them go up, down, up, down, frequently. Once you get a sense for that, you will have a better idea of when to grab your tickets. All that said, as a general rule, as things get close (less than 5-6 months before departure), the passage of time usually will not get you less expensive seats, so don't wait too long.

As others have mentioned, start looking at prices now and be ready to pull the trigger if you find a deal. Be sure to look at travel blogs around Thanksgiving for potential Black Friday/Cyber Monday deals. Also, be open to flying into somewhere OTHER than Sweden and catching a cheap flight from there to your final destination. For example, flights from Sioux falls to Stockholm in June are running $1300-1500 now. If you can find a deal to say, Frankfurt for $600, you can find a cheap flight within Europe for a couple hundred more at most. Maybe even less than $100. I use Google flights for international travel and skyscanner.net for intra-European flights.

I have 2 different ways that I purchase airplane tickets:

1. I see a great deal and book it and plan around it.
2. If I already have a destination, I start to monitor flights at about 10 months out and book when the price is at a level that I am comfortable with and quit looking. Sometimes it gets a little cheaper and sometimes it doesn't, but as long as I can get it at a price I am comfortable with I don't worry about it.
   

Poke around online and look at historical average fares, so you know what price to target. Check fares now, but more than likely you will find better deals at around the 6-months mark before departure, but could find something sooner, or later. Also, check the deals pages on sites like Boarding Area, Points Guy, etc., and play around on Kiwi, Kayak and Google Flights - often you'll find fares that are really good if you're flexible on dates, so if you can go +/- a day or two, you could save yourself some money.....and, most important, be ready to pull the trigger and buy your ticket when the fare is low. OH...and use INCOGNITO browser when searching, the airfares really DO increase the more you search particular routes and dates. Cheapest days to fly are Tuesday or Wednesday, and major holidays (the holiday, not before or just after).

I just bought tix about 1.5 weeks ago for travel from my home town in Tennessee into London and home from Barcelona in June 2019 for approx $650 rt. That same flight is now $1400+

There is no right or wrong time and no crystal ball. Sales happen in the blink of an eye. Monitor frequently

The one thing I'd keep in mind is what are the probabilities that life will throw you a curve ball and you wouldn't be able to go on the trip.

No one wants to think they'd have a job loss, expensive home repairs, serious health issue, or a work situation that will not allow time off. But, life happens. So, you'd just have to look at your own life situation