The beginning of a bull run in the cryptocurrency sector is characterized by a sustained and significant increase in prices over an extended period of time. Here are some common signs of a bull run:

1. Increase in overall capitalization: A rapid increase in the overall market capitalization of cryptocurrencies is often an indicator that the market is in bull mode.

2. Rising major assets: When Bitcoin and other major cryptocurrencies (such as Ethereum) start to rise steadily, they often pull other cryptocurrencies along with them.

3. Institutional investor interest: If funds, companies, or institutions show increasing interest, this can contribute to the triggering of a bull run.

4. Positive market sentiment: Social media and specialized media show a renewed optimism among crypto investors and influencers, reinforcing the attractiveness of the market.

5. Increased trading volumes: A sharp increase in trading volumes on exchanges is also a good indicator of the arrival or start of a bull run.

6. Economic cycles and special events: The Bitcoin halving (reduction in mining rewards) is often a catalyst for bullishness for cryptocurrencies, sometimes marking the start of a bull run.