Well, considering, that you are not a spambot, although some evidence points in this direction - sorry - the Germanic word for month (
month,
Monat,
måned,
mánuður,
maand) is derived from the word for moon (
moon,
Mond,
månen,
máninn, maan). So you may deduce from this, that the protohistoric Germanic tribes had a lunar calendar. But the earliest mentions of the term month is from Christian or medieval sources. For example the Gothic Bible of Bishop Wulfilas (4th century), Lukas I, 26, 36:
þanuh þan in menoþ saihstin insandiþs was aggilus Gabriel fram guda in baurg Galeilaias sei haitada Nazaraiþ, [...] jah sai, Aileisabaiþ niþjo þeina, jah so inkilþo sunau in aldomin seinamma, jah sa menoþs saihsta ist izai sei haitada stairo,
And in the sixth month the angel Gabriel was sent from God unto a city of Galilee, named Nazareth, [...] And, behold, thy cousin Elisabeth, she hath also conceived a son in her old age: and this is the sixth month with her, who was called barren.
The next source is the Anglosaxon monk Beda Venerabilis (English: Bede; 7th/8th century) in
De Temporum Ratione; he writes, that his ancestors counted the month by the course of the moon -
Antiqui autem Anglorum populi [...] iuxta cursum lunae suos menses computavere;
- and recalls the names of the months:
Si quidem apud eos luna mona, mensis monath appellatur. [...] Deinde Februarius Sol-monath, Martius Rhed-monath, Aprilis Eostur-monath, Maius Thrimylchi, Junius Lida, Julius similiter Lida, Augustus Vueod-monath, September Haleg-monath, Oktober Vuinter-fylleth, November Blod-monath, December Giuli, eodem Januarius nomine, vocatur.
A source of the 9th century is The Life of Charlemagne (Vita Caroli Magni) by Einhard. He writes how Charlemagne recalled the names of the month in his Franconian language:
Mensibus etiam iuxta propriam linguam vocabula inposuit, cum ante id temporis apud Francos partim Latinis, partim barbaris nominibus pronuntiarentur. [...] Et de mensibus quidem Ianuarium uuintarmanoth, Februarium hornung, Martium lenzinmanoth, Aprilem ostarmanoth, Maium uuinnemanoth, Iunium brachmanoth, Iulium heuuimanoth, Augustum aranmanoth, Septembrem uuitumanoth, Octobrem uuindumemanoth, Novembrem herbistmanoth, Decembrem heilagmanoth appellavit.