The Topic Sentence can go in any one of three (3) places in a paragraph: At the beginning (a form of Deductive Order , that is, going from the General or Main Idea to the Specific Support Sentences of that Main Idea in your organizing the paragraph);
http://www.csun.edu/~hcpas003/topic.html
1 Choose one of the following subjects on which to do so: (a) A Special Gift; (b) Your First Day of School; or (c) A Funny Television Commerical.  Definition. There will be occasion when you wish to define a term or process so as to add information in a Topic Sentence Paragraph.
http://www.csun.edu/~hcpas003/topic.html
The topic sentence is a sentence that is used at the beginning of a paragraph to tell the reader what it is that you are going to be talking about in that paragraph. It’s very similar to the thesis statement that you may have learned about if you took an English composition class, except on a much smaller scale.
https://blog.udemy.com/examples-of-topic-sentences/
All three paragraphs start out well with a topic sentence. A topic sentence is a sentence whose main idea or claim controls the rest of the paragraph; the body of a paragraph explains, develops or supports with evidence the topic sentence's main idea or claim. The topic sentence is usually the first sentence of a paragraph, but not necessarily. It may come, for example, after a transition sentence; it may even come at the end of a paragraph. Topic sentences are not the only way to organize a paragraph, and not all paragraphs need a topic sentence. For example, paragraphs that describe, narrate, or detail the steps in an experiment do not usually need topic sentences. Topic sentences are useful, however, in paragraphs that analyze and argue.
http://grammar.ccc.commnet.edu/GRAMMAR/paragraphs.htm
Cohesion Between the Topic Sentence and the Details (the Rest of the Paragraph) To reiterate: the topic sentence is the main idea, and the rest of the paragraph supports that main idea. Creating the cohesion needed between the topic sentence and the details isn't easy. You have to try, try again. Write and rewrite. But all that work is the art of writing.
https://www.sophia.org/tutorials/topic-sentences-and-supporting-details
1 Develop a Topic Sentence Paragraph that uses description as the primary method of development. Choose one of the following subjects on which to do so: (a) A Special Gift; (b) Your First Day of School; or (c) A Funny Television Commerical.  Definition.
http://www.csun.edu/~hcpas003/topic.html
1 Don’t use facts as topic sentences. Remember, you are using the topic sentence to introduce a point you are trying to make, or your opinion.  Don’t just talk about the “what” – talk about the “why” as well. That is, don’t just think about the effect, but it’s cause.
https://blog.udemy.com/examples-of-topic-sentences/
1 Develop a Topic Sentence Paragraph based upon the issue of AIDS by using a combination of illustrations, examples, and details.  Develop a Topic Sentence Paragraph that uses description as the primary method of development.
http://www.csun.edu/~hcpas003/topic.html
The topic sentence is important because it leads the reader into the points that you are trying to make, without leaving them confused. It also helps to prevent any miscommunication on your part. There are a few qualities that make for a good topic sentence: Brevity: Long, rambling sentences can be confusing.
https://blog.udemy.com/examples-of-topic-sentences/
On the other hand, there are a few things that make for a bad topic sentence. Be sure that you aren’t using these kinds of sentences to introduce your paragraphs, as they are unhelpful to readers and do little to help you get your point across. Don’t use facts as topic sentences. Remember, you are using the topic sentence to introduce a point you are trying to make, or your opinion.
https://blog.udemy.com/examples-of-topic-sentences/
which sentence does the topic sentence follow
The topic sentence is usually the first sentence of a paragraph, but not necessarily. The topic sentence is usually the first sentence of a paragraph.