Does seeing color on zinnias leaves and stem mean the flowers will bloom soon?

I am growing zinnias and they are growing great. I have grown them from seeds and about two months now. I started them around march 15 and I just noticed that two of the many I have has color on the stem and a little bit on the underside of the leaves its starting to get a pinkish color. Does that mean flowers will bloom soon?and if so how soon will they bloom.this is my first time growing these and would like an estimate on when the flowers will bloom.thanks!!Does seeing color on zinnias leaves and stem mean the flowers will bloom soon?
they usually flower from the start of July and can still flower if looked after well until mid October (also depending on the weather)