problem with dynamic day/night function with skylight cube map blend.

Hi everyone ,I am recently working on a VR project and I want to have a dynamic day/night function controlled by widget slider, a little bit like the day/night function in vr app “google earth”
I used “on value changed” on the widget graph and connect it to the skylight cubemap blend fraction with blueprint interface. It works well with just 2 cube maps. But I would like to have multiple maps for different time of the day, for the example I just used 4. So to approach this I used the “in range” not to determine which maps to load, but the problem is when the map switches it has this popping and flickering effect, it is no smooth at all.
also use “in value change” event to change the directional light rotation makes the sunlight flicks too.
I am new to UE4 I tried to figure this out by myself and I have been stuck for days, not to many information about cubemap blend out there, I found one from epic and it used a timeline, but I don’t know how to apply it with a widget control.
Is there any other way to approach this ? ( a dynamic day/night cycle with “direction light,sky sphere ,skylight” controlled by widget slider)
Thank you very much and sry for the poor English.

widget blueprint:
skylight blueprint: