Very straightforward trip. M1 to Newry then follow signs for AI towards Belfast. From Dublin Airport you are looking at about 1hr 30mins. Only possible delay at the moment is the roadworks outside Newry. Some days they are rock-blasting and delays of 15-20 mins are possible although from memory this usually only happens about one day per week and usually early afternoon.
That's an important point. Getting as far as Dublin Airport is hard to estimate, especially at that hour (pre 8AM) of the morning and if it is raining.
The last time I drove to Belfast, my journey time was 1h45m from Dublin Airport to the Odyssey Centre. As long as you're past Dublin airport by 8AM, you should make Lisburn by 9:30, even allowing for some time to locate the church.
If the cortege is arriving at the church for 9.30, would you be behind it for any part of the route? Depending on the route it takes to the church, other local traffic in the area might be heavy, and you might need to take this into account.
Thanks for all the info guys. I did get a chance to check last night but I hadn't time to reply. Anyway the trip took 1hr 50mins up and 2hrs back if anyone is interested. I left (D3 area) at 7.30am and arrived @ 9.20am.