"Early methods" is correct and usable in written English
You can use it when referring to methods that were developed or used in a earlier time period. For example, "Early methods of agriculture were much more labor intensive than current techniques."
Early methods of weed control included mowing, flooding, cultivating, smothering, burning, and crop rotation.
Early methods of producing cations involved oxidative reagents such as [Cp2Fe]+ (Eq. 2) or Ag+ [112].
Early methods of scatter reduction included the dual or triple energy window [9, 10] techniques.
Early methods involved evaluating tumor size and spread as well as histological assessment (tumor grade).
Early methods, graphical and analytic, were indirect in that they attempted to produce simple reference structures rather than simple loadings.
Early methods of fabricating customized radiation carriers for inaccessible areas, such as the nasopharyngeal space, normally required the patient to be under conscious sedation or general anesthesia to allow impressions for indirect processing techniques.
Early methods of protection, aside from the normal support of the extended family, involved charity; religious organizations or neighbors would collect for the destitute and needy.
Early methods to test key innovations using sister-group comparisons [54] have been shown to be biased by large differences in species diversity [55], and are prone to elevated Type I error rates [56], [57].
Early methods included pre-existing historical partnerships with on-going dialogue.
Early methods for estimating divergence times from gene sequence data relied on the assumption of a molecular clock.
Early methods for copy number analysis involve fluorescence in situ hybridizations and array-based methods (CGH arrays and SNP arrays).
