What happens is that people are required to go down to 3 schools (primarily OOS since Texas residents are down to 1 in Texas already) and so some are paring down their Texas admissions. It is upto the schools to decide whether they admit other OOS when they lose some or admit IS for those openings since OOS admissions are carefully measured (try to hold to 10% or less) sforo when they lose one, it is an actual opening for the school.
Early May they need to further reduce to a single admission which means some have given up 2 more admissions, whether in Texas or elsewhere. This is when IS students might actually give up a Texas admission to go OOS and slots can open up, normally at higher tiered schools causing a ripple effect. If nothing changes in the first 10-15 days of May, most likely the season is over. It is very rare that things happen after 15th if it does, it is primarily for someone with zero IS admissions.
edit: I see
@wysdoc is predicting movement only after 30th. The 2nd paragraph here is why.