ftb and ccb thresholds are very different - you can be over the threshold for ftb adn still get some ccb - however, if you're not sure of income, or happier to have a clean calculation (like the 50% ccr) then yes, this is the way to do it
as long as both of you are working/studying/training you will get the ccr payment. if you opt to withold ALL ccb you may be entitled to until tax time, you get the FULL 50% CCR - up to the maximum amount per year (7500). if you receive ANY CCB payment through the year, your CCR is dropped to 42.5% of your bill, with the other 7.5% held until tax time, as a safety net. you will still be entitled to the same amount, but the timing of payment varies.
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