each time

xxxたびに Every time.
(xxxつど) Pretty much the same! But 都度 is used with more abstract, lofty things. You wouldn’t say “Eating some hash browns 都度 I use Tabasco.”
ついでに～ (jissho kei v.) As long as you’re doing xxx, do yyy as well. As long as you’re in the kitchen, grab me a beer.