Thank you. I am interested in how to determine the details of the earlier names of my relatives in Germany .
Your query is quite general. Start by looking up the names in Menk's "Dictionary of German-Jewish Surnames".
This will hint at the towns where the surname came from. Pages 3&4 of the book give the dates when surnames were mandated in various parts of Germany. Pages 106 and following give references to many of the source documents.
To give one example that you mention, Tiktin may have been used in Breslau as early as 1737, which makes it quite an early Ashkenasi surname. But, as a toponym (from the Polish town of Tykocin), it may have been adopted by several unrelated families at different times in different places.
In a previous posting (from October 2020), I gave a link to a publication listing 3755 Jewish name adoptions from Silesia, dating from 1814. However, page 3 of Menk's book makes clear that the district around Breslau took surnames in the 1790s, so the surname Tiktin does not appear in the 1814 list.
I hope this helps a bit,