Here is an assortment of useful links for historical fiction in the 17th century.
Calendar for 1624 France.
Multi-country historical calendarHistorical calendars for the years 1000 to 2100 for 13 different countries. The calendar in use for a particular year varied from country to country for many centuries and this is a handy way to sort out the difference between Julian and Gregorian dates. (http://www.arc.id.au/Calendar.html)
Six Millennium Catalog of Phases of the MoonPhases of the moon from (2000 BCE to 4000 CE).
This allows you to generate a lunar calendar for a date and location. Here is the lunation for Paris, France in the year 1624. The site can generate lots of other useful stuff.
US Navy Observatory
Generate Rise/Set/Twilight tables for Sun or Moon from 1700 onwards .
Money and Costs
Databases on Money and Pricing for the Early Modern Period. This provides a source for actual prices of some things, while many prices are for commodities, there are some useful prices for things an adventurer or noble might buy.
A History of 17th Century Europe
Henry IV Website: http://www.henriiv.culture.fr/#/en/uc/00_00_05
The total population of France circa 1600 was 20,000,000
The Huguenot population circa 1610 was just under 1,000,000
The Huguenot Population of France, 1600-1685: The Demographic Fate and Customs of a Religious Minority, by Philip Benedict, Publisher: American Philosophical Society, (ISSN 0065-9746) page 75, Table 18.
Dutch (United Provinces)
Russia and Poland
Illnesses and Cures from the Middle Ages
A useful resource for playing a Healer or Apothecary