Hamstring Pull/Strain

Minor muscle strains usually heal on their own in about a week or less, especially if there is no bruising. If there is bruising your muscle strain is typically classified as mild to moderate and healing can take 1-3+weeks (on average, depending on severity) To improve healing, do light activity and stretches, ice the are within the acute stage/first 2-3days or so, followed by heat on the area of sore muscle. I would not recommend doing any activity/exercise that causes the pain to go past a 6 on 10 in severity (1=feeling awesome, 10=worst pain ever) while you are healing. In otherwords, a little pain is o.k., while you heal, but don't expect to be doing what you did before you were injured. Avoid plyometrics, box jumps squatting and also sprinting. Hamstrings are more prone to taking a while to heal because they are a powerful 2 joint muscle, and if you don't let it heal properly, it can be a chronic thing. If you're still worried about, contact a health care professional.
I would also suggest intramuscular stimulation/dry needling also works really well for chronic hamstring injuries (usually done by physios), or ART, done by chiros and physios.

If you're stretching it, stretch for 30s for each stress, stretch into tension, not pain, repeat throughout the day.