I feel you OP. I'm stuck there as well. At this rate (assuming I time it perfectly), I'm gonna need 48 hrs to get the next 5000 I need to open milk chest.
Afaik, the only way to accelerate this is to cash in on blue gems but I don't have much and wanna save it to get epic/legendary cards instead. I got the time, but I'm also not sure how long we got to complete this event. Did they say? I wanna get them all done before the event expires oof.