Use Package :later keyword like the old :idle keyword

use-package-later.el

(eval-when-compile
  (require 'use-package))

(add-to-list 'use-package-keywords :later t)

(defalias 'use-package-normalize/:later 'use-package-normalize-forms)

(defun use-package-handler/:later (name keyword arg rest state)
  "Handler for `:later' keyword in `use-package'."
  (let ((wrapped-arg
         `((run-with-idle-timer 0 nil (lambda ()
             (condition-case err
                 (progn ,@arg)
               (error
                (message "Error in %S :later evaluation: %S" ',name err))))))))
    (use-package-handler/:preface name keyword wrapped-arg rest state)))

(provide 'use-package-later)