A quirk of Pinterest's API causes your existing pins to arrive in a single batch when you first add a Pinterest source. Future pins come through with the correct date stamps.
When you first add a Pinterest account or board to your Juicer feed, the posts arrive in one batch rather than spread by their original pinning dates. They look as though they were all posted at the same time, which can place them all at the top of your feed.
There is no workaround for the initial import — but future pins arrive in your feed with the correct date stamps, so the feed naturally evens out over time.
What you can do
Set post order to "Random". Open the feed's settings, find the Post order dropdown, and pick Random. Posts then reshuffle on each feed refresh (the refresh interval depends on your plan), so Pinterest doesn't permanently dominate the top of the feed.
Add Pinterest first. If you haven't added other sources yet, add Pinterest first so its initial batch is followed (and pushed down) by other sources you add afterward.
If Pinterest pins keep clumping after the first batch — meaning new pins don't arrive with sensible dates either — send us the Pinterest username or board URL and the feed name through contact us.