Impots - How to setup monthly payment

Well having done the online 'impots' last night at the end of it - Kerching. Looks like yet again more bloody tax to pay. *groan*

Whilst not a vast sum, I'd still rather setup to pay monthly (with OH autoentrepreneur, for cash flow reasons it'd be better.) I went to the little 'rubique' to set this up, but it needs an 'avis' number?

Now last year I did not set this up as we got a refund (and we couldn't do it online as it was the first time.) Or will we get hammered again like on the Habitation where we only got the bill for the first time last year but were too late to setup as monthly.

I think the deadline is June 30th, but will we get the 'avis' before then?