As I said, in Greek, there is no comma.
I say to you today you will be with me in paradise.
Only in English (or another language) would that cause an interpretation problem. The answer to your question though is, they both died that very day thereby answer the question: when would he be in paradise? That day. I hope this helps.
There would only be an 'interpretation ' problem if it was in fact translated wrongly and the comma was put in the wrong place and thus say what was not said or leave it so vague that gives room to the devil to work his mischief.
That you say has no punctuation does not give licence when translating into English to put it wherever you like .
For if ALL scripture is inspired by God .Then THE meaning of the passage or words that were spoken and recorded is clear according" to the mind of God" For the Spirit knoweth the mind of God"
Hence the need if not more so for the Spirit of God to lead us into all truth in Greek as much as it was needed to understand what was written; as it is needed to understand it in English .
Those who misstranslate the scriptures do so at their peril for clearly they were simply led by the foolishness of their own reasoning (at best) that by the Spirit of God.
in Christ
gerald