I updated a company file from SA 2008 to Sage 50 2018.1 last month to send to an accountant.  I opened the file in 2018.1 and updated it.  I did the same thing with my own file last week from Sage 50 2013.2 to 2018.1.

As long as you have at least 2015 on your system, you should be able to open it and upgrade directly to 2018.  I do happen to have versions going back to 2004 plus multiple releases on my system, but it is not necessary.

It can take a while because there are two database version changes where all the data is dumped and reimported, but if the file size is small, it's not long.  Just be aware that some dialogs near the end show up under windows on a second monitor if you are doing other things while the update is happening, so if nothing is happening for a while and task bar icons disappear for a long time, start minimising your windows and you will likely see the dialogs.

Thank you Richard. I have 2015 on my computer, so I will try the upgrade and let you know how it goes.

When doing data conversions like this, I always work with temporary files on my C: drive, rather than working on the server.  It seems to be much faster that way.