The time now became so bad for alts that I have sold many of my alts at break even. I had bought many alts with BTC and even though the price of alts has increased in USDT, they have performed poorly with respect to BTC. I sold many of my coins at break-even just to regain my positions in BTC. So you never know when to sell. There are some coins which I sold at 25% profit and I would say that's a comfortable price.
That's what exactly, you will never know when to sell but at least you have an aimed profit for it and 25%-30% is fair enough to get a profit when the market becomes a bull trend. I guess don't be a fool if you will sell your bitcoin at a lower price, you should have a wait when is the perfect time of selling since we all know the market was in sudden price go down or sometimes it will go up.
In my own, when you see profit in your portfolio, don't hesitate to sell if you really need it financially because for me, when I needed the most money I sometimes manage my portfolio selling a small portion on it.