Today I found the never-seen-before insects on my Inaba Shidare maple and was able to identify them as a cottony maple scales (they are identical to the picture below, only in a much lesser quantities).

I know I'm not allowed to use insecticides on jap.maples beside the point that scales should be attacked at the proper time which I don't know when.

Infestation is not severe yet, but already noticeable.

I didn't observed any visual damage. Again, yet.

What are my remedies beside hand pick and/or insecticidal soap?

Here is a link that might be useful: {{gwi:259750}}