Are there times of the year that are better to submit than others, or
There’s not a huge difference in when you submit, it just may take longer to get a response.
Timing is more important with the smaller publishers than with the bigger ones because the small ones have each of their employees wearing several hats (ex: editor also does marketing). For those smaller publishers, the big LDSBA is in August, so July and August might take longer to get through the process. Also Thanksgiving, Christmas and New Years–give or take a week on either side. Then there’s summer vacations–and there’s no way you can know when that will hit.
Many publishers will create a budget for a specific time span–usually yearly, quarterly. As it gets closer to the end of those time periods, they may have used up their budgets and not really be looking hard until the beginning of the next time period. Or, they may have extra money and be a little less picky just to get something out there. (Not a good plan, but it happens.)
However, regardless of when their budgets begin and end or when they take their vacations, if your book is good enough, it will overcome those obstacles. If their budget is spent, they will hold it over until they have money again.
So, long answer to a short question, No, it doesn’t really matter when you submit.