H1B VISA with PERM Process Inprogress


Kindly advise me on below.

I am on H1B Visa and I am closure to H1B 6 years max out period. My visa will be valid only till first week of June. My employer has recently filed Prevailing Wage Determination with DOL. I have applied for H4 with future date. I heard from our immigration team that I can stay on H4 after H1B Max out and I can be back on H1B again once Perm & I140 is approved.

Kindly suggest me if I need to get priority date(Perm filed with DOL) before my H1B Max Out? As per the PWD processing times, It is taking for 4 to 5 months for hearing from DOL. Just want to know if I will be eligible for 7th year extension after I140 approved or do I need go for fresh H1B(365 Colling period) in this scenario? Please suggest me If I am on right boat or missing here anything.