You can take a week's worth of EI chemicals, mix them in separate bottles etc.

Add like 500mls of water with 1.5 teaspoons of KNO3 for example(3x 1/2 teaspoon for a week).

Add 500mls/3 three times a week. Or 167mls 3x a week.

Same type of thing for KH2PO4 and GH if you want/need.

Regards,
Tom Barr