Granted, weaning in those days took place much later than in our culture. Age three to five was the standard, but I have read in one source that it could occasionally be stretched to age 8. (I don't remember where I read that.) I would never ascribe my own feelings to Hannah, but I would say that if I were her, I would have not been in too much of a hurry!
But here is something to think about today: Who was she leaving this young child with? Eli, the high priest. Sounds like an excellent mentor, doesn't he? But Eli himself had not done such a good job with his own sons. Now the sons of Eli were worthless men. They did not know the LORD (1Sam 2:12). These men were priests mind you, who disobeyed God's directions on dealing with the sacrifices that people brought. Chapter 2 goes on to describe that and then says this, Thus the sin of the young men was very great in the sight of the LORD, for the men treated the offering of the LORD with contempt (1Sam 2:17). And this might not have been the worst of it. Now Eli was very old, and he kept hearing all that his sons were doing to all Israel, and how they lay with the women who were serving at the entrance to the tent of meeting (1Sam 2:22). Notice: everyone knew what they were doing.
In case you were wondering, Hannah and her family lived in Ramathaim (1:1), the Old Testament name for Arimathea in the New. My Bible map shows it to be less than 20 miles from there to Shiloh where the sanctuary stood in those days. Certainly close enough for news to travel. Now you are Hannah and you realize the kind of men Eli's sons are, men he raised himself. What are you going to do with the child you have promised to take and leave there?
The first thing to notice is that Hannah did not use this as an excuse to go back on her vow to God. She made the vow, her husband allowed the vow to stand, and that settled it. But I bet not a day went by that young Samuel did not hear the Pentateuch quoted in his home. I imagine his mother and father both taught him every moment they had, and even made sure to make those moments happen. They knew that not only would they not be there to teach him, but the influence he would be surrounded by would be less than optimal, to put it mildly.
After Samuel arrived, God required the lives of those three men within a few short years, the father and his two wicked sons. (I am not certain how old Samuel was at that time. Josephus says he was 12 when Eli died, but Josephus did not live then and, although he is considered reliable in the period between 100 BC and 100 AD, for the very early Jewish history he only repeated the historical traditions. Numbers 4:3 says that a man could not serve as priest until he was 30, and Samuel was not only prophet and judge, but also priest eventually. That might mean that the people lived without a high priest for a period of time or perhaps another Aaronic descendant stepped up. We simply do not know.) Samuel lived several years in that wicked atmosphere after his mother took him there. Yet he turned out a righteous man. Hannah, unlike Eli, did her job and did it well.
What we seem not to realize is this—we are in exactly the same situation as Hannah. Sooner or later we will turn our children over to other influences, whether public school or even a religious private school, and eventually a university probably. And that does not count the even earlier influences of society in the things they see on television, or the things they read, or the video games they play, or any number of other things. Are you diligently preparing them for that time? Will they be able to see wrong and know it is wrong? Will they be strong enough to be different from their peers, even revel in the difference as Daniel, Shadrach, Meshach, and Abednego did?
Time flies faster than you think. I am sure those early years flew for Hannah. They are flying by for you as well. Remember that before it is too late.
Then the LORD said to Samuel, “Behold, I am about to do a thing in Israel at which the two ears of everyone who hears it will tingle. On that day I will fulfill against Eli all that I have spoken concerning his house, from beginning to end. And I declare to him that I am about to punish his house forever, for the iniquity that he knew, because his sons were blaspheming God, and he did not restrain them (1Sam 3:11-13).