How do you start and manage therapeutic SC heparin for acute thrombosis in pregnancy as the patient approaches delivery?

Assume patient requires anticoagulation in the setting of acute thrombosis, with no need for IVC filter, but is approaching the end of her third trimester with anticipated delivery date weeks away. However, she would like to transition to heparin to increase likelihood for obtaining neuraxial anesthesia. Do you always give an IV heparin bolus in clinic before starting subcutaneous dosing, or would you even consider admitting patients for this process? How do you select your starting dose of heparin and do you dose adjust based on PTT?