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If you look at 2 here, you will read that by closing your business for part of the week may help to keep your turnover down. However, that advice is really aimed at a business which will has the option to only be open for a part week on a permanent basis.
The rules for registration are here. The key words for me are "expecting" or "knowing" that you will go over the threshold in the next 30 days. You appear to know that you will do that in the next 4 days. I have heard of small shops closing for a week or so to to avoid the threshold but I would say that HMRC will take a dim view if they found out what the real reason was as opposed to a business owner's claim that the closure was due to illness or holiday. However, unless HMRC carry out a VAT audit at some point after you have registered and spot the apparent closure of the business for a few days very close to the threshold, it may go unnoticed. There are penalties for not registering when you should have.
I hope this helps but let me know if you have any further questions.