Ok, first of all you do NOT want to use a systemic if your plants are budding. I'd rather not see you poison yourself or others. In general I will not use systemics though due to the health risks so I might be a bit biased towards them.
The best defense against botrytis is cultural practices and genetics. Avoid purple kush, bubba kush, or any of the other very afghani-dominant indoor strains as they have almost zero resistance to botrytis. Usually strains that produce big dense buds will be the most mold prone but not always. Generally strains that are more sativa-ish tend to be resistant. Unfortunately that does not do you much good this year.
For mold I use Oxidate (h2o2) - a light spraying every 3 days can usually keep it mold in check. Stylet oil can also help prevent it as well. Always be sure to cut out any mold you find too. However Oxidate only works if you keep on top of it. Botrytis is systemic, once you see it start to mold up on your buds that means most of the plant is infected. I usually figure if I start finding mold in more than 2 or 3 spots on a plant it is time for it to come in. The oxidate works on contact only, so if your plant has been infected to the point where the mold is growing up the stem and in the cores of the buds it will not be very effective.
Oh, also proper pruning will help keep it in check. You want to always clean out all that wispy crap in the core of the plant. This will help with air flow which is important in preventing mold.
The other option is try to increase your air flow externally. I have seen people put big fans in their outdoor garden to keep the air moving so this technique is not just limited to indoor grows. I was actually contemplating getting a few battery powered fans to place in the core of my plants this year during the fall.
