Late-to-Early Training: LET LLMs Learn Earlier, So Faster and Better

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Main Authors: Zhao, Ji, Gu, Yufei, Shao, Shitong, Zhou, Xun, Xiang, Liang, Xie, Zeke
Format: Preprint
Published: 2026
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author Zhao, Ji
Gu, Yufei
Shao, Shitong
Zhou, Xun
Xiang, Liang
Xie, Zeke
author_facet Zhao, Ji
Gu, Yufei
Shao, Shitong
Zhou, Xun
Xiang, Liang
Xie, Zeke
contents As Large Language Models (LLMs) achieve remarkable empirical success through scaling model and data size, pretraining has become increasingly critical yet computationally prohibitive, hindering rapid development. Despite the availability of numerous pretrained LLMs developed at significant computational expense, a fundamental real-world question remains underexplored: \textit{Can we leverage existing small pretrained models to accelerate the training of larger models?} In this paper, we propose a Late-to-Early Training (LET) paradigm that enables LLMs to explicitly learn later knowledge in earlier steps and earlier layers. The core idea is to guide the early layers of an LLM during early training using representations from the late layers of a pretrained (i.e. late training phase) model. We identify two key mechanisms that drive LET's effectiveness: late-to-early-step learning and late-to-early-layer learning. These mechanisms significantly accelerate training convergence while robustly enhancing both language modeling capabilities and downstream task performance, enabling faster training with superior performance. Extensive experiments on 1.4B and 7B parameter models demonstrate LET's efficiency and effectiveness. Notably, when training a 1.4B LLM on the Pile dataset, our method achieves up to 1.6$\times$ speedup with nearly 5\% improvement in downstream task accuracy compared to standard training, even when using a pretrained model with 10$\times$ fewer parameters than the target model.
format Preprint
id arxiv_https___arxiv_org_abs_2602_05393
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Late-to-Early Training: LET LLMs Learn Earlier, So Faster and Better
Zhao, Ji
Gu, Yufei
Shao, Shitong
Zhou, Xun
Xiang, Liang
Xie, Zeke
Computation and Language
Machine Learning
As Large Language Models (LLMs) achieve remarkable empirical success through scaling model and data size, pretraining has become increasingly critical yet computationally prohibitive, hindering rapid development. Despite the availability of numerous pretrained LLMs developed at significant computational expense, a fundamental real-world question remains underexplored: \textit{Can we leverage existing small pretrained models to accelerate the training of larger models?} In this paper, we propose a Late-to-Early Training (LET) paradigm that enables LLMs to explicitly learn later knowledge in earlier steps and earlier layers. The core idea is to guide the early layers of an LLM during early training using representations from the late layers of a pretrained (i.e. late training phase) model. We identify two key mechanisms that drive LET's effectiveness: late-to-early-step learning and late-to-early-layer learning. These mechanisms significantly accelerate training convergence while robustly enhancing both language modeling capabilities and downstream task performance, enabling faster training with superior performance. Extensive experiments on 1.4B and 7B parameter models demonstrate LET's efficiency and effectiveness. Notably, when training a 1.4B LLM on the Pile dataset, our method achieves up to 1.6$\times$ speedup with nearly 5\% improvement in downstream task accuracy compared to standard training, even when using a pretrained model with 10$\times$ fewer parameters than the target model.
title Late-to-Early Training: LET LLMs Learn Earlier, So Faster and Better
topic Computation and Language
Machine Learning
url https://arxiv.org/abs/2602.05393