Bitcoin entry price is absurd. Before we thought it wouldnt reach 30k then it surpass that then some think it wouldnt reach 100k but we also surpass that. We cant say they arent right about their prediction but let see. A turn around is also quite possible since we dont know what the market holds or current trajectory.
But you could always do dca on buyng bitcoin. At least it will average your entry if its low or high from current market price.
Time in the market is important but how long you can let your position opens in the market depends on many things, not only on your will. It mainly depends on your capital management, like what is origin of your investment capital. If it is a loan money, it's risky and unsustainable for your investment, and you can not hold your position for long time as consequence of loan expiration.
If it is your own money, it's good, but another important thing can affect your position and time in the market. It is how small or big your investment capital is in your whole capital?
If it is 100% of your capital, it's risky too and you will have weak hands when market crashes or emergency will force you selling your bitcoin.
It is only good if it is a small or not too big part of your capital, and you have reserve for other activities beyond Bitcoin investment.