Leaving feedback is optional.
Sellers can only leave positive feedback (been that way for almost 10 years now).
The big sellers who leave feedback generally do it when they ship stuff out -- because they are handling too many transactions to do more than a generic message.
Smaller sellers divide into 3 camps -- those with forgetful memories who leave feedback when shipped, those who never leave feedback (can't be bothered, or don't like the positive-only choice), or those who wait for feedback from the buyer. I'm in the last camp, I leave feedback when the transaction is completed -- when the buyer has the item and is satisfied with their purchase.
You mention 60 days, which sounds like purchasing from China -- which is really slow in arriving these days (the current highly toxic drug scare is one of the slowdown reasons -- unregulated in China but banned in Canada).
If getting feedback is important, then look at the feedback for a seller before buying. You can select to see just the feedback the seller left buyers -- and see if you want to purchase.
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