Statistically, going all-in is going to work out better more often simply because the markets generally go up over time. However, drip-feeding (AKA cost-averaging) reduces risk.
My main advice is… don’t over-think it. You can’t out-smart the market, and the one time you manage to out-smart it, it will do something dumber than you could have imagined and you’ll be wrong anyway.
Of course, you can also split the difference and put 1/3 or 1/2 in now, and then cost-average the rest through the year