[curiosityshop]

Ok, I've never been good at grammar, and this is true of all the languages I've learned or grown up knowing. I'm trying to get to grips with what word order to use when forming sentences in Japanese (although I've read somewhere that the Japanese don't actually have sentences? o.O). So, could a native speaker please confirm whether the following statements and phrases are correct?

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In general, Japanese word order goes Subject, Object, Verb.
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You can usually have time and place words before the subject and object, but not between the object and verb, or after the verb?
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You could write "Sometimes, I go to school on Sundays" as:

"Tokidoki watashi wa doyoobi ni gakkoo ni ikimasu."

"Doyoobi ni watashi wa tokidoki gakkoo ni ikimasu."

"Tokidoki doyoobi ni watashi wa gakkoo ni ikimasu."

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Another example. "Yuko is going back to Tokyo tomorrow"

"Yuko-san wa ashita Tokyoo ni kaerimasu."

"Ashita, Yuko-san wa Tokyoo ni kaerimasu."

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Are all of these variation ok to use? Or are there any that could be used but just don't sound good so they're not usually used in that order?

Thanks in advance ^^