Most vendors are simply drop-shippers so your miners will almost always arrive from China, direct from manufacturer.
Whilst it is not unusual to pay large sums of money and not receive equipment for several months, this industry is absolutely fraught with scammers and fraudsters - there is a high risk of losing your money if you don't do the correct / adequate research and ensure you are buying from a reputable seller. Further, scammers will copy the websites and telegram addresses of reputable sellers so even if you think you are dealing with a reputable seller, it may be a clone website or username etc.
I would recommend getting yourself setup on telegram and joining some of the channels detailed here, where you can check authenticity of sellers, report or ask about potential scammers etc:
https://to.tools/verified-sellershttps://t.me/asicMinerChannel - this is a great Telegram channel for hardware listings and deals, as only verified sellers can post in this channel
From the vendors listed there, I can vouch for HashExpert and Kaboomracks, both of which I've made successful purchases through - but once again you MUST take every precaution possible to ensure you are dealing with the genuine seller and not a clone...