Just do the math and pay close attention to the markets. Things are really volatile (bouncy) in Canada so yearlings are not for the faint hearted.
We grass a few, have bought grassers in the past and try to sell when there is profit. Last year despite our plans to grass all our calves the price reached a point that was well above our projected profits. That was in March before the grass was growing so we pulled the marketing trigger and only grassed a few later calves. There are usually peaks in early spring for calves to go to grass and August for calves coming off.
KNOW YOUR BREAKEVEN!!! It's OK to leave some grass behind if the profit is there. If you have time and a bit of patience there is real money in upgrading cattle (buying tailenders, age verifying, dehorning, castrating, vaccinating, etc).