You have two different options to start your presentation from a particular slide.
Option 1:
- On the left side of the screen click the slide from which you want to start your show.
- Go to the Ribbon.
- Choose Slide Show tab.
- Click From Current Slide button.
- Slide show will start from the current slide and will go till the last slide. First slides will not be showed at all.
Option 2:
- Go to the Ribbon.
- Click Slide Show tab.
- Choose Custom Slide Show button.
- From the drop down list click Custom Shows option.
- New dialog box appears.
- Click New.
- Type Slide show name.
- Check Slides in presentation which you want to show.
- Click Add button.
- On the right side of the screen put your slides in order using down and up arrows.
- Click Ok and close the dialog box.
- To start click Custom Slide Show button again and choose it from the list.
Option 2 is way better. It gives you much more possibilities.