I am guessing most of this is going to happen from units produced in Shanghai's GF3?
GF3 is only for Greater China (China, Taiwan, Macau, Singapore). Everywhere else is GF1/Fremont. Eventually GF4 will serve Europe.
As for when things will happen when:
UK/Ireland: June
Other major RHD countries (Australia, New Zealand, Japan): Unsure - has anyone heard whether they'll be June like the UK/Ireland, or are they later?
Iceland: Seems to be targeting a couple months from now.
E. Europe: Some places adjacent to their current markets seem to be targeting a couple months from now, although it looks like it'll be quite a while before they cover all of E. Europe.
Brazil, India: I seem to recall them talking about targeting next year for them. Both very large car markets (with enough wealth disparity to provide for a sizeable middle class), but both are relatively raw ground for EVs.
Russia: Good-sized market, but I haven't seen a target date.
S. Korea: Haven't seen a date, but I'd imagine that it shouldn't be too long from now; it's a pretty solid EV market with big ambitions.
Middle East: Tesla already has operations in a few countries, but no Model 3s yet, and I haven't seen dates for when they'll be arriving. They apparently got permission to open operations in Saudi Arabia late last year. Car sales volumes are only moderate in the big Middle East markets, but ASPs are high.
Rest of the world: Seems like they're targeting ~2 years or so from now. The numerous small markets in lower-income countries will have a lot of overhead relative to the number of sales.