I'd advise following SpeedwayIMP Instagram page here: https://www.instagram.com/speedwayimp?igsh=MWl3eThlMGdhN25pNA==
and additionally the Ostrów FB page here: https://www.facebook.com/share/1B9k5W3MfU/
Between the two, you'll find out soon enough when tickets go on sale. Be warned, buy them immediately they are on sale as they'll sell fast. The first time I went to Ostrów was for an SEC event in 2016 I think and there seemed to be hardly anyone anywhere in the town two hours before when we walked to the stadium. When we got in, we were shocked to find not one seat still available and we had to stand at the back, behind rows of others. There were 16,000 there with a capacity of 12,000!
For Ekstraliga it entirely depends on where you are going. Wrocław has sold out every home meeting for the last 3 or 4 years and tickets are gone in moments. Lublin, almost impossible. Grudziądz is ok if you are happy to sit on a bend otherwise buy within 2 minutes of sale starting. Leszno is easier as there the capacity is 16,700 and average crowds this season so far are 13,000. Toruń, again, be quick, depends on the opposition. Zielona Góra, big stadium, doesn't sell out and there's discontent this year with the team. Częstochowa, no issues at all. Gorzów be quick but you'll get good tickets.
Tickets usually go on sale about 7-14 days beforehand.