Actually, everything starts counting after you apply for the benefit, but since masteries and trading achievements are things you can hold off until you decide to turn them in, those are somewhat 'stackable'
For deck donations and game rounds it works differently: since donations are reset every month, only the donations you turn in after applying for the benefit will count and the game rounds will start counting after you apply as long as you receive the rewards on the same date as the day of your benefit application, if that makes sense. These are not stackable in the sense that you can't count those after you complete the number of rounds you need for the first benefit as rounds for your second benefit, you start from 0 rounds for each benefit application.
I hope this answer your question and I apologize that it was so confusing.
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For deck donations and game rounds it works differently: since donations are reset every month, only the donations you turn in after applying for the benefit will count and the game rounds will start counting after you apply as long as you receive the rewards on the same date as the day of your benefit application, if that makes sense. These are not stackable in the sense that you can't count those after you complete the number of rounds you need for the first benefit as rounds for your second benefit, you start from 0 rounds for each benefit application.
I hope this answer your question and I apologize that it was so confusing.