H1b transfer with new employer after joining old employer within 60 days grace

[winner2019]

Hi All,
I have couple of questions for my case of H1b. Please advise me on this.

i94 valid till June 2019. About 5 years in current H1b.
OLD Employer - laid off on Dec 2018
Old employer did not withdraw H1b petition.
Rejoined Old employer on some project on 1st Feb 2019.
Old employer ran pay stub for Dec 2018. (might be running stub for Jan 19 as well).
New employer is filing H1b transfer now.
Do i need to join new employer within 60 days or i can join after 60 day also?
Am i still considered in 60 days grace period even if i am joining my old employer back and they did not withdraw my H1b petition?