An important feature of the trade mark system around the world is the six month priority period. This is incredibly helpful for all businesses whether big or small.
The world of trade marks operates on a first to file system. This means that the first person to file a trade mark is the first owner of the mark. But sometimes you're not sure which trade mark you want to go for (or which will be granted) and you don't want to spend a lot of money filing a trade mark in lots of different countries only to discover that it can't be granted. The international priority system solves this problem.
Trade mark priority is very simple. You have six months from the date that you file a trade mark to file the same mark elsewhere in the world and claim a "priority date" of the filing date of the earliest trade mark. The day of filing is not included in the calculation.
For example, if you file a trade mark in Switzerland on 29 July 2018, you have until 29 January 2019 to file a trade mark in the EU, US and China which can claim a priority date of 29 July 2018.
If you miss the priority deadline, you can still file a trade mark but if someone else has filed an identical or similar trade mark in the meantime, they will likely be able to successfully oppose your application to register your trade mark.