BTC/USD: long position from support area(H4)

At H4 chart BTC/USD looks the same like H1. You can clearly see up going trend line, which was broken. As a result, formed down going flag construction.
As for me, the best chance to buy BTC will appear when the price go to the strong support area from 54000 to 55000.

The strength of this level is also confirmed by the Fibo level of 50%.
Stop-loss should be under the strong buyer impulse.
If I were you, I would prefer to keep position for a long time.