Hi, You can make the mix up (without the DMSO) and put it in the refrigerator, DMSO will inactivate the MMS, but the activated MMS (MMS/Citric Acid/ wait for activation, add water) will last a good long time in the refrigerator.
You do not need to use the entire 50mL on your cat at a time, You just need to get the cancers wet (which is why the spray bottle comes in handy) - then once you get them wet with the MMS/ you can put the DMSO on top and rub it in slightly. You can also spray the DMSO on top. (Separate spray bottle) -
If you mix the whole thing at once (MMS/ Citric Acid/ wait for activation, add water, add DMSO), then you will have to mix a new batch each time, no matter how much of it you used on the cat - because DMSO - which is wonderful for getting the MMS deep into the tissues - also will inactivate the MMS in about 20 minutes.
And yes, do it hourly - if the cat has a problem with the DMSO (irritation, etc), then you can back off with that, for a bit, and continue with the MMS until the irritation gets better, then start again with the DMSO.