If you are concerned about the quantity because I said "dichromate is not particularly dangerous to have in small quantity" then consider the following. Keep a clean bottle compatible with dichromate (such as brown glass or opaque plastic) and transfer a month's (or a few months') worth of use of the agent to it. Keep the master bottle tightly closed, boxed in a safe place. This way, in case of the worst accident, the amount of exposure to dichromate is limited to what you have in the small bottle.

Control of every bit of small exposure is important for some agents with different kind of toxicity, but with dichromate, I would put more focus on minimizing accidental exposure to it.