You're referring to the D minor etude, I assume? The ordering of Op. 39 has a lot of ambiguity, for reasons I'm sure I was told at one point but can't be bothered to remember.
If so, I'd personally recommend choosing another piece. That etude is arguably one of the hardest of the set, and from your current rep (C# minor prelude and g minor prelude) it'd be quite a step up. Plus, with 4 months you might get a little rushed, and with a monstrous piece like that, that's almost a guarenteed disaster.
EDIT: Just realized I was mistaken, it's the E flat minor etude. Still a big piece, but it's more approachable than the D minor IMO.
Still, same principle applies. If it's really far out of your reach (and it seems quite a distant from the two aforementioned preludes) and you only have 4 months, I'd pick another piece.