Hi Racheal, I'm a VBAC'er also and I have had OB's tell me I should get to the hospital earlier in labor because of the need for continuous fetal monitoring. Getting to the hospital early is really only necessary if your labor is progressing quickly, if you've got cause for concern such as a large amount of blood or discolored fluid discharge. Unless it's really medically necessary, like your doctor has specific cause to believe there is a complication, it is just as effective to ask for what hospitals sometimes refer to as a 20 minute strip. This is when they monitor for 20 minutes out of each hour, and after a few "strips" they will sometimes lay off even longer as long as there is no cause for concern.
Also, ACOG has changed it's views on constant fetal monitoring over the past 2 years. Initially they recommended constant monitoring and OB's and hospitals went overboard with it, making it a near requirement for a hospital birth. Some hospitals still have this policy, although some doctors don't follow it. In 2010 they re-issued their practice bulletin, updating the finding that intermittent fetal monitoring is just as effective, and can be done by both by EFM and fetal dopptone (the device they use in a doctors office to hear the heartbeat). There have also been several studies that site constant monitoring and epidural as being part of a group of interventions that can lead to higher rate of Cesarean, based on the fact that both essentially limit the ability of the mother to move during labor, making the pelvic bone much more inflexible and inhibiting the ability of the baby to move into position. I'm a prime example of that fact, since I was also induced in my first pregnancy and my body wasn't ready to have the baby, so the meds, epi and constant monitoring made it so impossible for my son to descend the birth canal that when he was born by Cesarean he actually had a small dent in his forehead.
The thing to consider is this: if you have a rupture, or more likely a dehiscense since rupture is pretty rare, you will be able to tell. Dehiscense (a small window of opening usually in one end of your uterine scar that can leak fluid into the area between your uterus and your skin) comes with pain, sometimes bloody discharge, and often a bubble or bulge in the skin on the outside of the body. Rupture is much more painful, and often comes with pain in the diaphragm and shoulder, as well as a greater amount of bloody discharge and again, the skin near your scar can look bulged or discolored. Most ruptures happen fairly early in labor too. So, if you are laboring at home and notice any of these symptoms then I'd say get to the hospital asap. If not, you probably have no reason to rush in and spend a day or two being "observed" flat on your back attached to machines in your bed. I've never heard of a normal, healthy mother (and yes, a VBAC is included in that statement) needing to leave for the hospital until contractions without signs of problems were 5-6 minutes apart.