In the past 4 years of marketing successful crowdfunding campaigns on both Kickstarter and Indiegogo, we've consistently seen drops in consumer traffic to these sites during the holiday months, as potential backers are purchasing products for the holidays that they can gift, not necessarily backing projects/products that will ship next year.
I think you just answered your own question. Crowdfunding efforts take at least 6 months of planning, marketing strategy and stakeholder engagement. You are also trying to avoid noise from competing efforts or that could take away attention from your target market. If you are just starting down this road then I suggest doing your research and begin engaging in January to set the foundation for a launch around April like previous expert has indicated.
If you're in a rush, launch your campaign asap. The closer to Christmas you get, the less attention people will direct at crowdfunding opportunities. If you are not in a rush, I would launch your campaign between March and July - there seems to be more activity during this period. Of course, my advice also depends on your product. If it's relevant for this seasonality (e.g. New Year's resolutions), the timing couldn't be better. Think about how that can possibly be leveraged.
In addition to the answers already provided, I would add that January and even February are poor choices to launch a campaign. People are short on cash and have exhausted their "charity resources". If you can, wait. And use that time to spark your community and plan your campaign. Good luck!