Answer: March through July is ideal for seeding, but if this is a mild year you might make some headway since you are only patching, but certainly don't wait. The reason is that this is a warm season grass and it does not actively grow in the winter. It can also be damaged by oscillating temperatures, more so when it is still beconming established. Your local county extension may have some ideas on what you need to do to prevent bare patches (eg soil preparation tips), or you may find some tips at the following web site.
Good luck with your lawn!
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