Yes, this is possible on GCN. huge sequence break. :D Credit to me for the positioning and angle of the Twilit Messenger and being first to do it, credit to Kazooie for his "Sacred grove early (maybe)" video which really helped because it showed where the standable spot is and how to get to Sacred Grove after making it up, and credit to SexyZora19 for many of the ideas behind the trick and Super Jump. This is a difficult trick; make sure the Twilit Messenger is in the right spot and you're jumping from the right angle. Also make sure you release the attack standing as close to it as possible right when it's about to attack you. Don't give up if it takes a while to get it correctly. If you need to practice on everything after the jump up, I recommend doing what Kazooie did in his video "Early sacred grove (maybe)" here:
After getting up, turn into a wolf and practice all you want. Also try NephTheFish's Infinite Bombs & Arrows trick so you don't have to worry about running out of bombs:
Anyways, back to Early Master Sword. if you're having trouble with the jump to Sacred Grove, then don't worry about it; if you miss the jump, the entrance appears on the minimap. Angle yourself towards the entrance before you jump. Doing this leads to plenty of interesting glitches, some of which I'll have in a small compilation of Early Master Sword glitches I'm uploading soon (hopefully today). You'd need to try it for yourself, though. :P If you finish the Forest Temple before you restore light to Faron, you'll need to howl at a Howling Stone so you can get the Finishing Blow, because the wolf won't appear at the entrance to the Forest Temple. Have fun!
EDIT: NOTHING MORE ABOUT SEXYZORA. She's gone. Deal with it. Any more comments about her will be deleted, and further insults will result in being blocked.
EDIT: Also, if you're trying to jump to Sacred Grove's entrance but the game thinks you're falling to your death and respawns you, I think the problem is you need to get a little higher up and climb the hill a bit more. I'm not positive that that's how to fix it, but it's my best guess.
EDIT: Thanks to badger989, we've got an NTSC Wii save of Early Master Sword!
NTSC Wii (File 2): ndex.php?dlid=248 - Sacred Grove right after Master Sword - by badger989
PAL Wii (File 2/3): = Outside Kakariko after taming Epona/Sacred Grove before Master Sword - by Faentaass
Any other saves would be appreciated. PM me the link to them if you get one.