Gerudo Training Grounds

[OracleOfAwesome]

What's the earliest possible point it can be completed?

 

[Krazy4Krash]

There are 9 keys to collect in the Grounds and only 7 are required to get the Ice Arrows reward. You need a different dungeon item to collect one key. That is, the fairy bow to get one, megaton hammer to get another, etc. One you have enough items to get 7 keys, you can navigate through the maze to get the Ice Arrows.

 

[SpiritGerudo]

I'm going to assume you know about the Gerudo Training Grounds because you got to the Gerudo Desert (and thus have all dungeon items before the Spirit Temple and have already done the Shadow Temple), so: I'm 86% sure that you need the first dungeon of the Spirit Temple, the Sliver Gauntlets, which means that you will need to do at least the child (first) portion of the Spirit Temple before you are able to complete the Gerudo Training Grounds.

 

[MW7]

There are 9 keys to collect in the Grounds and only 7 are required to get the Ice Arrows reward. You need a different dungeon item to collect one key. That is, the fairy bow to get one, megaton hammer to get another, etc. One you have enough items to get 7 keys, you can navigate through the maze to get the Ice Arrows.

Exactly, I researched this before and this is what I came up with:

Note that everything that follows is without glitches.
I confirmed this myself:
2 keys require something to fight with (i.e. the sword)
1 key requires the Song of Time
1 key requires another key (the one in the room of locks)
2 keys require the bow
1 key requires the megaton hammer
1 key requires the iron boots
1 key requires the silver guantlets

So this means at a minimum you need:
1. bow and megaton hammer
2. bow and iron boots

The silver gauntlets don't factor into this because you would have to get the iron boots and longshot to get the silver gauntlets without any glitches (so it would be an extension of option 2). This means that you can obtain the ice arrows after entering the Forest Temple for the bow and then either the Ice Cavern for the iron boots or Fire Temple for the megaton hammer.