As a prominent VC once told me, the best time for entrepreneurs to raise money is when they don’t need it. VCs can smell desperation a mile away. If you really need money, then you are by definition desperate and easily subject to a down round where your investors, and you, get crammed down.
So when there’s money out there and you have a strong business case to raise it, do it. Because you never know when the financial markets will turn and if you need money, you either won’t get it, or the terms will be onerous.
Of course, the flip side of this is the danger of having too much money too soon in a startup, a problem and post for another day.