I’m sitting here, enjoying a lovely rootbear float, which I’ve been doing quite often lately. Something I realized though, is usually a float by definition, you pour the drink, and then put ice cream on top. I’ve never done this (at least when makinga float for myself. When I worked at a restaraunt, I’d always do it by the book) I’ve always found it much more enjoyable when you put the ice cream in, first though. More ice cream is dissolved in the drink, and you don’t get the nasty spill over as long as you pour carefully. Which way do YOU prefer?
I like the ice cream first. When I get one at a restaurant, I always dunk the ice cream under the soda before I eat it.
Former soda jerk here. We put the ice cream in first, covered it in root beer, and then put a “sidecar” (an extra scoop of ice cream) on the side of the glass rim.
My dad worked at a soda fountain in the '50s, and he taught me to put the ice cream in first, pour the soda, and add another scoop of ice cream to float on top.
Ice cream, then drink. I’ve never seen it done the other way around. I thought that “float” meant that ice cream will float in the drink, which does not depend on the order of insertion of the ingredients.
If the ice cream doesn’t go in first, the person who made it is indeed a “soda jerk” 
I really don’t care for the whole “sidecar” business. It’s messy and if trhe ice cream has been put where it belongs it’s redundant and superfluous.
I’ve always found it difficult to add the soda to the ice cream; it foams up so much that it overflows violently before even a couple of ounces of soda have been added. I suspet this might be because I’m using the wrong ice cream though.
Yes, the secret is to bring the can of root beer with you when you go sit down with the float.
The BEST part of the float is eating the foam that forms on top. You want a thick layer, so you can slurp that up then add more root beer to make more foam to slurp up to make more room to add more root beer to…
Definitely ice cream first. Usually you’ll have to pour it, then let it sit a few seconds, then pour some more. But that’s ok. Good drinks take time.
As an aside, has anyone else had a Mt. Dew Livewire / orange sherbet float? It’s surprisingly good.
At our old ice cream store, we’d stick the ice cream to the side of the cup, kind of near the top, and then pour in the rootbeer on the side, avoiding the ice cream until it was about half full or so. Then it’d foam up the right amount while still giving you at least some rootbeer to drink.
I’ve found what works best is to pour in a tiny bit of soda, then drop in the ice cream, followed by topping off the soda. This yields a great head on the float, even more so with chocolate ice cream and root beer.