HI there, I wouldn't worry about the die off from the diet alone. Die off from antifungals maybe much more of an issue, so if I were you, I'd avoid them if you can and stick to the diet.
The diet will simply deny the yeast food and the numbers will reduce naturally, starving them out. You will no doubt get die off, but it will be a yeasty die off and not the one antifungal might produce (as they split open candida cells and any mercury there will be released into your system). At least diet is gentler and more natural and the yeast basically die through sheer starvation.
It can take around 3 weeks to improve if you stick with the programme. Cheating can force a person to have to start from scratch, it's not worth it to cheat. Die off can begin early on, like within about 5 days or so (this is what I've read and experienced), but some take even longer for it to occur.