Heya! Thanks for the kind words! :D (That means a lot in this... sometimes-stressful time)
For the doggy tail scene, it's an automatic scene if you keep spending time with him on weekdays (the afternoon spending time), same with the playing with dog scene (it's not triggered after getting pet). The dog costume is after you play with the dog (MC wonders how good Shiba will look with the doggy ears on, and the bear from love hotel suddenly comes to him and says he has the "goods" that MC wants => then MC can go to love hotel to pick up the doggy costume).
For the "special date" scenes, all of them are triggered automatically only after you've become lovers with the guy, So if you aren't lovers with the guy by that date, the scene won't trigger.