Blocks at the beginning is very common I guess, but for me only with certain words. The good part about blocks with only certain words is, I quickly put another word "well, ..." or "uhm" before the word i cannot say, and voila, I tricked my brain and the word gets out. I use this so frequently that nowadays I am not anxious at all and don't stutter. I recently discovered that in spanish (learning for a few years now) I tend to repeat the words, which never happens in my mother tongue or english. Since this is a new to me language I really do not care about it, lol.