I am having pretty regular contraction every 20 mins for pass 1 hr (Since 4 am). I was 2 cm dilated in the evening around 6 pm and had the bloody show at around 5 pm. Wondering if I should go into the hospital yet or wait for my water bag to burst? Or for contractions to be between 5-10 mins apart.

Since you already have regular contractions interval for every 20minutes and had bloody show, you should head to hospital immediately. My labor kicked start after bloody show, i.e. more intense contractions and nearly unable to reach hospital in time due to traffic jam in the morning. Thus, to play safe you should head to hospital soon. For my both deliveries, I do not have water bag burst but mid-wives helped me to broke the water bag instead during 10cm dilation.