I think they all sound good
from a word-order point of view except I think maybe the second tokidoki example sounds a bit off. But I'd wait for a native speaker to weigh in on that one. To me, it's just weird to hear "On Wednesday first" because it prepares me to think about the upcoming Wednesday. Then all of a sudden "tokidoki" and I'm confused a bit. But like I said, wait for a native to weigh in on this one. My comments are just a quick placeholder.
Now, your first three sentences all sound bad because of the "watashi wa" in them. Japanese people would leave it completely out of the sentence for almost all conceivable occasions. The only time that actually comes to mind is if you wanted to say something like "Now I, on the other hand [as opposed to Yuko-san or someone], go to school sometimes on Wednesdays."
Just ときどきがっこうにいきます would be fine without the わたし.