Outmoded word for "next Tuesday"

I am writing an email and wanted to refer to this coming Tuesday. The phrase "Tuesday est" popped into my mind (something Miss Marple might have said) but when I googled it I could find no reference. I have a feeling that 'est' isn't correct, but there is a word or I presume an abreviation that sounds like it that means next. Could you please tell me what it is?

Aha! I have just had a brain wave, it isn't 'est', it's 'inst'. Is that right? What does it stand for?

Inst is an abbreviation of the Latin 'instante mense', meaning the current month. Prox ('proxime mense') means next month and ult ('ultimo mense') means last month. These terms were once used in correspondence, but are used now, if at all, only by the terminally abstruse.