Well, disregarding what has already been said about your mannerisms.
To your question.
Honestly, jump back and forth between multiplayer and the whatever singleplayer campaign you're playing. They're both basically completely independent from each other. Play some Octo Canyon/Octo Expansion for a little bit, once you've had your fix, jump into multiplayer, or vise vera.
Honestly, don't sweat the order, just play whatever you want whenever you want. Though it would still be recommended you completely Octo Canyon first, before Octo Expansion if you haven't already. Octo Canyon is a good tutorial for both multiplayer and to warm you up and the harder levels seen in Octo Expansion.
Unless you are really itching to play the Octoling, in which feel free to binge Octo Expansion.