"Until then" is a phrase commonly used to denote a period of time before something else happens, but sometimes using the same phrase repeatedly can feel monotonous and unexciting. Here are some options to mix it up: "In the interim," "Pending," "In the meantime," "For a while," "Up to that point," "Prior to that," "Before then," "In anticipation," "Till that time," "Leading up to," "Until such time as," and "As long as." These synonyms can help to avoid overusing "until then" while adding variety to your writing or conversation and keeping things fresh and engaging.