You didn't say how old your tree is. They tend to take 2 years to flower and up to 3 years to give a good show, They tend to flower earlier in the year. Here in the UK this is around April/early May. However it does depend on the weather and your location, the warmer the climate the earlier they flower and there have been years where we had blossoms in March, Sour cherries flower earlier than the sweet varieties. If your tree is old enough to flower, the blossoms only last a short time and can be made even shorter by weather extremes such as strong winds, and heavy rains of couse when this happens it's also going to affect the crop of cherries.
By the way if you have a sweet cherry make sure it's a self fertile variety or one where two or more varieties are grafted on the rootstock, if not you will need to consider adding another variety in order for the trees to set fruit,