There is no "first time" clause in the visa waiver for Ireland. The conditions are very clearly mentioned on the website of Irish Department of Justice. To quote:
"In order to avail of the programme you must have landed and gained lawful entry to the UK on foot of your current UK visa, prior to undertaking the journey to Ireland.
Each distinct period of leave to remain in the UK (up to a maximum of 180 days each time) requires a prior legal entry into the UK before travel to Ireland under the programme, no matter what the duration of the UK visa."
Please note this is distinct from the BIVS (British Irish Visa Scheme) which is only applicable to Indian and Chinese citizens who are resident in their countries of citizenship. You will not get a BIVS endorsed visa from Germany. Ireland allows holders of BIVS endorsed visas from UK to enter Ireland directly if they have once traveled to the UK.
You can read the details here: