The long lead-time will prove useful as you will be able to sort a number of details.
Paper maps backed up by a GPS should work. If you take photocopies then these can be burnt or buried, or left in huts. After Hotham it's reasonably straightforward, although there are some sections where feral horse and other tracks make it confusing. I strongly suggest taking maps showing escape routes. A road map may suffice. You could write down escape route details and leave these with the escape route maps in each food drop.
John's track notes are pretty accurate, although there have been quite a few changes since publication. There's an article in BWA February 2019 about the AAWT, with track information that may assist
https://drive.google.com/drive/folders/ ... VI0OC1QdlUThirty days is possible, but may be pushing it a bit. Once you reach Johnnies Top it gets easier.
You need to check that the water tanks in the Barries and elsewhere are not burnt and have potable water. There was a lot of ash in the air a few months ago. There's been talk of tanks being put in at The Knobs and Viking Saddle, making those days far easier. The next tank after Barry Saddle is East Riley Road, 10 kilometres, with no camping at the tank, too steep. I'd pick up enough water for that night and the next day, go down to the road, then continue on a gentle climb for about 600 metres to the crest. South Selwyn has a tank with nice camping in trees. If you are in the vicinity, consider putting in a food and water drop at the bottom of the Johnies Top climb. The last potable water is the Mitta Mitta, and it's longish day from there getting to Johnnies Top, with a big climb.