The Gonzo,
So, the Eire issue got debated a little and we will start the genuine Eire colonisation of the East Coast in 1450.
Accordingly, when you are drafting the storyline and events, you have until then to have a fully independent storyline. After that point, you need to wrangle with the big issue, which is how the Vanlanders will respond to the Irish and how the Irish will respond to the Vinlanders.
I look forward to reading your ideas!