Upgrade from J 2.5.28 with EL 1.0.2 to J 3.x with JEM 2.2.x

Its time for me to upgrade my Joomla 2.5.28 with EL 1.0.2 to latest and greatest Joomla 3 with JEM 2.2.x.

My question is, as I can see that JEM 2.2.x is also supported on Joomla 2.5.x, which upgrade path to choose?
1) First upgrade Joomla 2.5.28 to Joomla 3, and afterwards upgrade EL to JEM?
2) First upgrade EL to JEM on the existing Joomla 2.5.28, and afterwards upgrade Joomla to 3?
3) Other (i.e. something I've missed)

Thanks for any assistance on this.

/Jonas

Oh, some more thorough searching revealed this: www.joomlaeventmanager.net/forum/jem-2-2-x-on-joomla-3/10155-solved-problems-simplelist-after-update-el-to-jem-and-joomla?start=6#23994

I will first update EL to JEM on my existing Joomla 2.5.28, and then upgrade to Joomla 3 afterwards.

So, it took a few attempts (thought I wanted to share for others)...

Short version
If you come from Joomla 2.5.28 with EL 1.0.2, then you can not import to JEM using "Eventlist import" in JEM 2.2.2 (at least it failed for me). However, using JEM 2.1.6 to do the import worked.

Longer version
I installed JEM 2.2.2 and went to Import. It found the EL tables alright, and I initiated the import. However it ended/failed with "Invalid Token". When I checked the db tables only the JEM Categories table was filled, the rest was still empty.
I then tried a number of different approached using CSV import and SQL table copy. I managed to get some right, but was still missing how to populate the "j25_jem_cats_event_relations" table.
Then I thought, that initially the import from EL to JEM had to have worked, as I assume lots of users used it. And there could be a real chance that no one ever upgraded from EL to JEM using JEM 2.2.x.
So, I uninstalled JEM 2.2.2, dropped all the SQL tables, and installed JEM 2.1.6, and did the import with success using "Eventlist import". Only one thing to mention, none of the events are listed in the Events list after the import, they are all set as Archived, so you have to go and "Un-archive" all events.

EDIT:
I found out why all the events got set as Archived. This is due to the default setting to archive events after one day. So all events more than one day old will be set to Archived.
If you, like me, would like to see all old events, just Un-archive them, and change the setting to never auto archive.

Whats next
I'm now on Joomla 2.5.28 with JEM 2.1.6. If I go to "Update check" it says "Update server currently not available. Please try again later!". Is this because "Update check" only works with Joomla 3.x?

So, should I now proceed to upgrade Joomla from 2.5.28 to 3.x, and afterwards upgrade JEM to 2.2.2? Or should I upgrade JEM to 2.2.2 first?

Hi, please backup first!
I think, this doesn't matter.
Me personally, I would trying to update JEM first. There was a change with the updates, so you have first to download JEM2.2.2 from here.
And after going to Joomla! 3.

Sure, I will backup before starting the J3 migration

How to update to JEM 2.2.2 then? Should I simply upload the JEM 2.2.2 pkg using Extension Manager - Install - Upload Package File? Will it simply overwrite the installed JEM 2.1.6?