Contacting seller is optional, like if you have some quiery.
And about other question, it depends upon which shipping method did u select.
As far as my experience concerned, "China Post Ordinary small packet plus" did not reach to me, well, because it is free shipping, and not registered, so it may reach you or not.
Others like "Aliexpress standard shipping" and "China post registered airmail" have always arrived because they are registered. And they took 11-18 days max to arrive.
Now the tracking scenario, well these 3 mails do not have tracking enabled, so you wont get tracking info after the parcel left china. Only expenaive Shipping methods do provide tracking, like DHL etc
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