DS1 is 3 years 9 months. I am German, my husband is British.
When he was born, it was my intention that he would grow up fully bilingually (knowing of course that, as he'd go to nursery, his English would be stronger).
Unfortunately, I have slipped into the habit of speaking far too much English with him, mostly because my husband's German is very weak and it is just sometimes easier that way. He does understand pretty much everything I say, but doesn't respond in German (he uses the occasional single word).
However, in the last month or so, he seems to get more interested in German, occasionally asking me "What's that in Deutsch?" or similar. He has also occasionally responded in German when I asked him to repeat a German phrase after me (e.g. "Ich will Wasser").
Should I harness this new interest now to try and make a new start with German? A friend of mine always asks "Wie bitte?" if her daugther does not respond in German. We are going to visit the German grandparents in two weeks, so will have a good chance for some immersion at that time.