I think Alex may have captured it in his post on 18 Mar, starting to rise, but I'll have to double-check it. If it is, it would be the earliest image of it I think. Do you have a date and time for that shot Alex? Thanks.
Edit: Yes, that is definitely the new nova Alex, congratulations! THe ASAS-SN survey first picked it up at about 6:47pm our time (AEDST) on 16 March, even though it wasn't announced until yesterday. Yours will at least be the first known image outside the discovery survey (so far) but IISers may be able to go back further again!
Cheers -