You are half way there if you touch the bow into the v of the trailer. Yes you do need to make sure your trailer is at proper depth to allow power loading. After having both roller and bunk trailers I use this rule of thumb.
Roller trailer: Back in until 2 sets of rollers are wet.
Bunk trailer: Back in until 1/2 the bunks are wet.
Then just center boat between bunks/rollers as best you can and give a LITTLE throttle, just enough to touch the bunks and stop. Then steer to re-center on trailer and touch throttle again. You should feel the boat being centered on trailer as you slowly drive it on. if not, back off and try again. If so, keep pushing slowly on until you touch the mast roller. If a roller trailer, leave motor in gear and reach down from the bow and secure your strap and safety chain. If a bunk trailer, shut motor off and you should stay on trailer without a strap.
Practice this.
Go to a small, lightly used ramp and launch and load til you get the method down.
Please don’t be the guy who hoards a busy ramp for 15 minutes while others wait in line.
I once watched a guy from my boat start to COVER his boat while still on the ramp as a line of trucks waited to launch. Not sure if he made it out of there alive.
Good luck!