it is good to have estradial below 50 the first few cycle days. what happens is that too much estradial early on promotes an 'unhealthy' egg. It's best the follicle allow time to grow before being developed.
Example: if the follicle is too small, say 4 mm, and estradial is too high (above 50), it starts to develop the follicle before the follice is ready resulting in a unhealthy egg.
So, it's best if follice can grow before adding in high amounts of estradial.
Hope this helps!