Custom Period Column Related to Today

YellowSquirrel , You have create a 444 or 445 calendar

DAX Calendar - Standard Calendar, Non-Standard Calendar, 4-4-4 Calendar
https://www.youtube.com/watch?v=IsfCMzjKTQ0&t=145s

Then you need to have a period rank

based on period start date

Period Rank = RANKX(all(Period),Period[Period Start Date],,ASC,Dense)

This Period = CALCULATE(sum('Table'[Qty]), FILTER(ALL(Period),Period[Period Rank]=max(Period[Period Rank])))
Last Period = CALCULATE(sum('Table'[Qty]), FILTER(ALL(Period),Period[Period Rank]=max(Period[Period Rank])-1))

This period today =

var _rank = maxx(filter('Date', Date[Date] =Today()) , Date[Period Rank])

return

CALCULATE(sum('Table'[Qty]), FILTER((Period),Period[Period Rank]= _rank  ))

Last period today =

var _rank = maxx(filter('Date', Date[Date] =Today()) , Date[Period Rank])

return

CALCULATE(sum('Table'[Qty]), FILTER((Period),Period[Period Rank]= _rank -1  ))

Time Intelligence, Part of learn Power BI https://youtu.be/cN8AO3_vmlY?t=27510
Time Intelligence, DATESMTD, DATESQTD, DATESYTD, Week On Week, Week Till Date, Custom Period on Period,
Custom Period till date: https://youtu.be/aU2aKbnHuWs&t=145s