you need to find out what is the official procedure for register as unemployed in Ireland, and where the addresses for the Irish employment services - or what they are called in ireland, are.
Like in Denmark - I assume that what is important is that the employment service office have registered that you have contactet them, submitted your U2 form to them, and told them that you are unemployed. I am not sure if this is done automatically by your A-kasse, so that the authorities in Ireland already can see your U2 document in their computers (online portal). But you could ask your A-kasse about this also.
In Denmark all these things can be done online - I am not sure in Ireland - you must check out how to do it.
We have on our site a guide about the unemployment insurance system in Ireland (however be aware it has not been updated recently)... but here you can find contact addresses in ireland etc.
The 7 days deadline must be taken serious - and I can not really understand why 7 days not will be enough for you.
As mentioned what is important is that you go to the office - I can not imagine that you need to book meeting before - but if you need to then you must do this in good time.
You need to be carefull about keeping the 7 days deadline - otherwise you could loose right to benefits.
I am not aware if its possible to do excemptions to the 7 days deadline - but maybe ask your A-kasse about that.