It is an important psychological principle that once a developmental window closes, it is much harder to re-open it.  For example, there is an optimum time for toilet training, when the 2-3 year old shows interest in mastery over his or her body.  If parents encourage this collaboratively, the child will enjoy meeting one of the first challenges in life — to renunciate instincts in favor of social status and competency.  If the child has a good experience with this, it will set him or her up on a good trend for life in appropriately managing urges.  If this stage is not negotiated well, it may take into 5 or 6 years of age to toilet train, and the child may continue to have frustration and ambivalence about when to “cooperate and hold it in”, and when to “let it out.”  It is not for nothing that obscene phrases that indicate refusal to cooperate or care often involve excrement.  Psychologically speaking, “I don’t give a _-_-_-_” is quite literally true.  The person is rebelling against feelings of being overly controlled and thus really refuses to give over control of his “_-_-_-_” to anyone.  This is also true with almost any developmental experience.  If the developmental window is not properly worked with, either by overindulging or by over-pressurizing, there will be lifelong ambivalences and struggles.  If you force a child to daven or read before he is ready, or if you don’t tune in and help him daven or master reading when he shows interest and ability, in either case, he will often be ambivalent and have complex and mixed feelings throughout life.

Our Gemara on Amud Beis discusses why the father of an underage bride should have veto power when the groom asks for the final step of the marriage to commence (nisuin):

אָמַר רַבִּי זֵירָא, תָּנָא: קְטַנָּה, בֵּין הִיא וּבֵין אָבִיהָ יְכוֹלִין לְעַכֵּב. בִּשְׁלָמָא אִיהִי מָצֵי מְעַכְּבָא, אֶלָּא אָבִיהָ — אִי אִיהִי נִיחָא לַהּ, אָבִיהָ מַאי נָפְקָא לֵיהּ מִינַּהּ? סָבַר: הַשְׁתָּא לָא יָדְעָה, לִמְחַר מִימַּרְדָא וְנָפְקָא, וְאָתְיָא וְנָפְלָה עִילָּוַאי.

Rabbi Zeira said: It was taught in the Tosefta (Kesuvos 5:1) with regard to a minor girl: Either she or her father may delay the wedding until she has reached majority. The Gemara asks: Granted, she, the girl herself, may delay the wedding if she feels she is not ready, as she is the one who will be directly affected, but why should her father be allowed to delay her wedding? If it is suitable for her to get married, what difference does it make to her father? The Gemara answers: He thinks: Perhaps she agrees to get married now because she does not fully know what she is doing. But tomorrow, she will realize the marriage was a mistake, rebel, and leave her husband, and then she will come back and become a burden to me. Therefore, her father prefers that she wait until she has reached majority and marry when she is completely aware of what is involved.

The logical question we might ask is, even so, if the girl must return to her father at a later time because she was not fully prepared emotionally for marriage, what does he lose out?  He is supporting her now, and would support her then  when she returns.  If anything, the father saves some money during the period of time that she attempted to live with her husband.  The obvious answer is, that if she is unable to handle the marriage and it falls apart, she may get divorced or at the very least, need to stay much longer at her father’s home to recuperate.  

The Gemara illustrates this developmental principle.  If you rush or push a life stage process to hard and prematurely, you do not just risk failing but you also risk losing more time than before, and even causing a lengthy disability.